Vitamin D levels, microvascular complications, and mortality in type 1 diabetes

Relationship between bone turnover markers and renal disease in elderly patients with type 2 diabetes: a cross-sectional study

OBJECTIVE

The prevalence of type 2 diabetes mellitus (T2DM) and bone metabolism disorders increase with age. Diabetic kidney disease (DKD) is one of the most serious microvascular complications of T2DM, and bone metabolism disorders are closely linked to the occurrence of DKD. The relationship between bone turnover markers(BTMs) and the kidney disease in elderly patients with T2DM remains unclear. Therefore, this study aims to investigate the association between common BTMs and DKD in a large sample of elderly patients. The goal is to provide a basis for early identification of high-risk individuals for DKD among elderly T2DM patients from a bone metabolism perspective.

METHODS

In this cross-sectional study, BTMs were collected from a cohort of 2,051 hospitalized Chinese patients. The relationships between 25-hydroxyvitamin D (25-OH-D), β-CrossLaps (β-CTX), osteocalcin (OSTEOC), intact parathyroid hormone (iPTH), and total type I collagen N-terminal propeptide (TP1NP), and DKD, as well as urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) were analyzed using regression analysis and restrictive cubic spline (RCS) curves.

RESULTS

Higher 25-OH-D levels were independently linked to a lower incidence of DKD and decreased UACR. The RCS curves showed a linear association of 25-OH-D and DKD, approaching the L-shape. β-CTX was independently and positively correlated with UACR. There is an independent positive correlation between OSTEOC and UACR and a negative correlation with eGFR. iPTH is independently and positively correlated with DKD incidence and UACR, and negatively correlated with eGFR. Additionally, the RCS curves showed a non-linear association of OSTEOC and iPTH and DKD, approaching the J-shape, and the point of inflection is 10.875 ng/L and 34.15 pg/mL respectively. There is an independent positive correlation between TP1NP and UACR incidence, and a negative correlation with eGFR. Risk estimates significantly increase with higher TP1NP levels in the RCS model.

CONCLUSION

BTMs are closely associated with kidney disease in elderly patients with T2DM. These discoveries potentially assist clinicians in establishing more preventive measures and targeted treatment strategies for elderly patients with T2DM.

Vitamin D deficiency and development of complications in individuals with type 1 and type 2 diabetes: A cohort study

AIMS

To investigate vitamin D deficiency as a risk marker for complications in individuals with type 1 and type 2 diabetes.

METHODS

A cohort study including 1448 adults with type 1 and 770 with type 2 diabetes. Individuals in the decile with lowest vitamin D level were classified as vitamin D deficient. Outcomes based on medical records and registers included mortality, major adverse cardiovascular event (MACE), heart failure, a composite kidney endpoint, albuminuria progression and sight-threatening eye disease. Risk in individuals with vitamin D deficiency was compared to the remaining using adjusted Cox proportional hazards models.

RESULTS

Vitamin D deficiency was associated with higher risk of MACE (adjusted hazard ratio (HR): 2.6; 95 % confidence interval (CI): 1.3-5.2) in type 1, but not in type 2 diabetes. Risk of heart failure was higher in individuals with vitamin D deficiency in both cohorts (HR (95%CI): 16 (4.8-50) in type 1 and 2.4 (1.1-5.5) in type 2 diabetes). Vitamin D deficiency was not associated with development of microvascular complications or mortality.

CONCLUSIONS

Vitamin D deficiency was a risk marker for MACE and heart failure in type 1 and for heart failure in type 2 diabetes, but not for microvascular complications or all-cause mortality.

Vitamin D deficiency contributes to the diabetic kidney disease progression via increase ZEB1/ZEB2 expressions

BACKGROUND

Diabetic kidney disease (DKD) remains one of the main causes of end-stage renal disease (ESRD) and mortality in diabetic patients worldwide. Vitamin D deficiency (VitDD) is one of the main consequences of different chronic kidney disease (CKD) types and is associated with rapid progression to ESRD. Nevertheless, the mechanisms that lead to this process are poorly understood. This study aimed to characterize a model of diabetic nephropathy progression in VitDD and the epithelial-mesenchymal-transition (EMT) role in these processes.

METHODS

Wistar Hannover rats received a diet with or without VitD before type 1 diabetes (T1D) induction. After this procedure, the rats were accompanied for 12 and 24 weeks after T1D induction and the renal function, structure, cell transdifferentiating markers and zinc finger e-box binding homeobox 1/2 (ZEB1/ZEB2) contribution to kidney damage were evaluated during the DKD progression.

RESULTS

The results showed an increase in glomerular tuft, mesangial and interstitial relative areas and renal function impairment in VitD-deficient diabetic rats compared to diabetic rats that received a VitD-containing diet. These alterations can be associated with increased expression of EMT markers, ZEB1 gene expression, ZEB2 protein expression and TGF-β1 urinary excretion. Decreased miR-200b expression, an important post-transcriptional regulator of ZEB1 and ZEB2 was also observed.

CONCLUSION

Our data demonstrated that VitD deficiency contributes to the rapid development and progression of DKD in diabetic rats induced by increase ZEB1/ZEB2 expressions and miR-200b downregulation.

Association of α-klotho with subclinical carotid atherosclerosis in subjects with type 1 diabetes mellitus

Background

Compelling evidence suggests that the fibroblast growth factor 23 (FGF23) / α-klotho axis is impaired in subjects with diabetes mellitus. We examined the relationship between parameters related to calcium/phosphate homeostasis, including FGF23 and α-klotho, and subclinical carotid atherosclerosis burden in type 1 diabetes mellitus (T1D) subjects.

Methods

This cross-sectional study involved 226 subjects with T1D and 147 age-, sex- and plaque-matched, non-diabetic (non-T1D) subjects, both with normal renal function. Carotid ultrasound was performed to determine the presence and burden of atheromatous plaques. Concentrations of the intact form of FGF23 and α-klotho were assessed by ELISA. Calcium, phosphate, parathyroid hormone, and vitamin D levels were also determined. Negative binomial regression models were used to examine relationship between parameters studied and subclinical carotid atherosclerosis.

Results

Only FGF23 was increased in T1D compared with non-diabetic subjects (> 2-fold; p < 0.05). α-klotho was higher in subjects with subclinical carotid atherosclerosis (1.4-fold, p < 0.05). Regression analysis revealed that the log α-klotho concentration was positively associated with the presence of subclinical carotid atherosclerosis both in T1D subjects (incidence rate ratio [IRR]: 1.41; 95% confidence interval [CI], 1.06–1.89; p < 0.05) and in non-T1D subjects (IRR: 1.65; 95% CI, 1.02–2.75; p < 0.05). The models also showed that age, smoking and albuminuria-to-creatinine ratio were positively associated with subclinical carotid atherosclerosis in T1D subjects. Interestingly, sex-related protection against plaque was also revealed in T1D women.

Conclusion

Higher α-klotho was associated with subclinical carotid atherosclerotic in the absence of kidney dysfunction. This finding also points to a new pathophysiological pathway involved in the development and progression of this complication.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01640-3.

Association of vitamin D status with all-cause mortality and outcomes among Chinese individuals with diabetic foot ulcers

AIMS/INTRODUCTION

The aim of this study was to examine the correlation between serum vitamin D concentrations and prognosis among Chinese individuals with diabetic foot ulcers (DFUs).

MATERIALS AND METHODS

We retrospectively recruited 488 adults with DFUs in West China Hospital from 1 January 2012 to 31 December 2019. After telephone follow up, 275 patients were finally included. We compared serum vitamin D concentrations among DFUs patients with different prognostic status, and examined the association of vitamin D status with prognostic variables by Kaplan-Meier analysis. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for all-cause mortality.

RESULTS

The median concentration of serum vitamin D of patients with DFUs was 37.78 nmol/L (interquartile range 27.91-50.66 nmol/L), with 31.6% having vitamin D deficiency (<30 nmol/L) and 42.2% having insufficient vitamin D (<50 nmol/L). During a median follow-up period of 52 months, 65 patients died, with an all-cause mortality of 23.64%. Vitamin D deficiency was independently linked to increased all-cause mortality after multivariable adjustments (hazard ratio 0.565, 95% confidence interval 0.338-0.946, P = 0.030). There were no significant differences between vitamin D concentrations and other outcomes of DFUs. Patients who suffered amputations had a tendency of lower vitamin D concentrations (34.00 [interquartile range 26.90-41.81] vs 40.21 [interquartile range 29.60-53.96] nmol/L, P = 0.053).

CONCLUSIONS

Vitamin D deficiency was significantly associated with increased all-cause mortality in Chinese individuals with DFUs. Vitamin D supplementation might be a potential therapy for DFUs to prevent premature death and improve outcomes.

Hypovitaminosis D and cardiovascular outcomes: A systematic review and meta-analysis

Background

The relation between blood vitamin D levels and the risk of cardiovascular outcomes is debatable. To our knowledge this is the first comparative meta-analysis of more than 100,000 patients' data with the aim to inspect the relevance of low vitamin D levels with adverse cardiovascular events.

Methods

Online databases including PubMed, Embase and Cochrane Central were queried to compare the cardiovascular outcomes among hypovitaminosis D (HVD) and control group. The outcomes assessed included differences in major adverse cardiovascular events (MACE), mortality, myocardial infarction, and heart failure. Unadjusted odds ratios (OR) were calculated using a random-effect model with a 95% confidence interval (CI) and P less than 0.05 as a statistical significance.

Results

A total of 8 studies including 426,039 patients were included in this analysis. HVD group was associated with a higher incidence of MACE (OR 1.92, 95% CI 1.24 to 2.98, p = 0.003), while there was no significant association of HVD and all-cause mortality (OR 1.77, 95% CI 0.75 to 4.17, p = 0.19), risk of myocardial infarction (OR 0.69, 95% CI 0.39 to 1.24, p = 0.22), and heart failure (OR 1.20, 95% CI 0.34 to 4.25, p = 0.78).

Conclusions

This meta-analysis suggested that low blood levels of vitamin D are associated with MACE, but no such difference in all-cause mortality, myocardial infarction or heart failure was observed. Appropriate supplementation of vitamin D in selected populations might be cardioprotective in nature and warrants extensive trials.

Vitamin D and Ocular Diseases: A Systematic Review

The contributory roles of vitamin D in ocular and visual health have long been discussed, with numerous studies pointing to the adverse effects of vitamin D deficiency. In this paper, we provide a systematic review of recent findings on the association between vitamin D and different ocular diseases, including myopia, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), dry eye syndrome (DES), thyroid eye disease (TED), uveitis, retinoblastoma (RB), cataract, and others, from epidemiological, clinical and basic studies, and briefly discuss vitamin D metabolism in the eye. We searched two research databases for articles examining the association between vitamin D deficiency and different ocular diseases. One hundred and sixty-two studies were found. There is evidence on the association between vitamin D and myopia, AMD, DR, and DES. Overall, 17 out of 27 studies reported an association between vitamin D and AMD, while 48 out of 54 studies reported that vitamin D was associated with DR, and 25 out of 27 studies reported an association between vitamin D and DES. However, the available evidence for the association with other ocular diseases, such as glaucoma, TED, and RB, remains limited.

Elimination of Vitamin D Signaling Causes Increased Mortality in a Model of Overactivation of the Insulin Receptor: Role of Lipid Metabolism

Vitamin D (VD) deficiency has been associated with cancer and diabetes. Insulin signaling through the insulin receptor (IR) stimulates cellular responses by activating the PI3K/AKT pathway. PTEN is a tumor suppressor and a negative regulator of the pathway. Its absence enhances insulin signaling leading to hypoglycemia, a dangerous complication found after insulin overdose. We analyzed the effect of VD signaling in a model of overactivation of the IR. We generated inducible double KO (DKO) mice for the VD receptor (VDR) and PTEN. DKO mice showed severe hypoglycemia, lower total cholesterol and increased mortality. No macroscopic tumors were detected. Analysis of the glucose metabolism did not show clear differences that would explain the increased mortality. Glucose supplementation, either systemically or directly into the brain, did not enhance DKO survival. Lipidic liver metabolism was altered as there was a delay in the activation of genes related to β-oxidation and a decrease in lipogenesis in DKO mice. High-fat diet administration in DKO significantly improved its life span. Lack of vitamin D signaling increases mortality in a model of overactivation of the IR by impairing lipid metabolism. Clinically, these results reveal the importance of adequate Vitamin D levels in T1D patients.

To the Question of Vitamin D Network in Type 1 Diabetes and Diabetic Nephropathy in Children Nursed in Ukrainian Endocrinology Unit

Background

Vitamin D deficiency is a great problem worldwide. Vitamin D plays an essential role in calcium and bone metabolism. Diabetic nephropathy (DN) is a dangerous kidney-related complication of type 1 diabetes (T1D).

Aim of the study

To evaluate levels of Vitamin D3 in pediatric patients with T1D and DN; to study the dependence between the Vitamin D level and main clinical and laboratory parameters of the disease, that is, duration, complications episodes, albuminuria levels, glomerular filtration rate (GFR).

Material and methods

A survey of 72 children with T1D and DN aged 3–17 years was done. Complex examination including conventional methods (physical examination, blood pressure measurement, blood tests, study of urinary sediment, renal ultrasound, etc.) was done for all patients. Data was processed using GraphPad Prism 9.0 Software for Windows (USA, San Diego, CA). p-values <.05 were considered statistically significant.

Results

Majority of patients from T1D group have normal value of Vitamin D, only 27.7% of children have Vitamin D insufficiency. In contrast, in children from DN group only 16.7% of children have Vitamin D insufficiency and 83.3% have Vitamin D deficiency. Vitamin D serum level negatively correlates with disease duration and albuminuria level in the group with DN. Serum levels of Vitamin D positively correlate with GFR in patients with T1D. Patients with DN who had a duration of T1D for 10 years and more have a higher progression rate to Vitamin D deficiency as compared to those who have a T1D duration of less than 10 years.

Conclusions

The authors conclude that Vitamin D has a direct relationship with functional disorders with DN, that is, albuminuria, GFR, kidney function. Further investigations of Vitamin D supplementation on different stages of the ND development and progression are needed.

Diabetic retinopathy risk prediction in patients with type 2 diabetes mellitus using a nomogram model

BACKGROUND

This study aims to develop a diabetic retinopathy (DR) hazard nomogram for a Chinese population of patients with type 2 diabetes mellitus (T2DM).

METHODS

We constructed a nomogram model by including data from 213 patients with T2DM between January 2019 and May 2021 in the Affiliated Hospital of Zunyi Medical University. We used basic statistics and biochemical indicator tests to assess the risk of DR in patients with T2DM. The patient data were used to evaluate the DR risk using R software and a least absolute shrinkage and selection operator (LASSO) predictive model. Using multivariable Cox regression, we examined the risk factors of DR to reduce the LASSO penalty. The validation model, decision curve analysis, and C-index were tested on the calibration plot. The bootstrapping methodology was used to internally validate the accuracy of the nomogram.

RESULTS

The LASSO algorithm identified the following eight predictive variables from the 16 independent variables: disease duration, body mass index (BMI), fasting blood glucose (FPG), glycated hemoglobin (HbA1c), homeostatic model assessment-insulin resistance (HOMA-IR), triglyceride (TG), total cholesterol (TC), and vitamin D (VitD)-T3. The C-index was 0.848 (95% CI: 0.798-0.898), indicating the accuracy of the model. In the interval validation, high scores (0.816) are possible from an analysis of a DR nomogram's decision curve to predict DR.

CONCLUSION

We developed a non-parametric technique to predict the risk of DR based on disease duration, BMI, FPG, HbA1c, HOMA-IR, TG, TC, and VitD.

Association of vitamin D receptor gene polymorphism with the occurrence of low bone density, osteopenia, and osteoporosis in patients with type 2 diabetes

Purpose

This study aims to analyze the association between VDR gene polymorphism and the occurrence of "low bone density (LBD)/osteopenia/osteoporosis" or LBDOO in type 2 diabetes (T2D) patients among a clustered population in northwest of Iran. The studied VDR gene polymorphism included ApaI (rs7975232), BsmI (rs1544410), FokI (rs2228570), EcoRV (rs4516035) and, TaqI (rs731236).

Methods

In this population-based cross-sectional study, patients with T2D were identified within a group of 1266 participants based on self-report of diabetes, history of diabetes medication, and recorded laboratory data. Separately for each polymorphism and gender, crude and adjusted (age, BMI) odds ratios (ORs) were calculated for participants with T2D through logistic regression analysis.

Results

The prevalence of T2D was 16.41% in people residing in the city of Sanandaj in 2011. Of the participants with T2D, 13.92% and 81.29% had osteoporosis and vitamin D deficiency, respectively. In women, the tt genotype of the TaqI gene significantly decreased the risk of LBDOO versus the Tt genotype, after adjusting for BMI and age (adjusted OR:0.18, CI_95%: 0.03-0.97). Conversely, the EE genotype of the EcoRV gene enhanced the risk of LBDOO versus the Ee genotype (adjusted OR:7.64, CI_95%: 2.03-28.72).

Conclusion

The polymorphism of both TaqI and EcoRV genes was associated with the risk of LBDOO in women with T2D. This is the first time a study has highlighted this effect for the polymorphism of the EcoRV gene; we believe that this study would serve as a basis for future studies.

Role of vitamin D in diabetic retinopathy: Pathophysiological and clinical aspects

Epidemiological data predict a dramatic increase in the prevalence of diabetes and of diabetic retinopathy (DR) - the most common complication of diabetes-for which however we do not have so far effective tools for prevention and treatment. Since hypovitaminosis D is very frequent in patients with diabetes and vitamin D (VD) has vascular protective properties, several studies have addressed the association of VD deficiency with DR and its severity and progression, whereas the effects of VD supplementation on its natural history are largely unknown. Here we review the available evidence that supports the possible protective role of VD in DR and suggests to determine the VD levels in DR patients calling for a definitive randomized clinical trial to ascertain whether VD supplementation could protect against DR.

Here for You: A Review of Social Support Research in Young Adults With Diabetes

Living with and managing diabetes is challenging during young adulthood, and social support may help relieve or minimize the burdens young adults with diabetes experience. This article reviews the types and sources of support young adults with diabetes receive and their associations with behavioral, psychosocial, and glycemic outcomes. Intervention research integrating social support and future directions for care are discussed.

Vitamin D Analogs Can Retard the Onset or Progression of Diabetic Kidney Disease: A Systematic Review

Introduction

Previous studies have shown that vitamin D analogs (such as paricalcitol) can reduce albuminuria in patients with diabetes mellitus and retard the progression of diabetic kidney disease (DKD). A recent systematic review reported significant improvement of renal function in patients with DKD who received vitamin D or its analogs. Study-driven data about their use in improving DKD outcomes have continued to accumulate over the years.

Aim

This paper aims to systematically review the contemporary evidence about the effectiveness of vitamin D analogs in retarding the onset or progression of DKD.

Methods

With appropriate descriptors, two electronic databases (PubMed and Google Scholar) were searched for articles published between 2015 and 2021 in the English language. Primary studies that fulfilled the inclusion criteria were selected; their titles and abstracts were screened, and duplicates were removed. Relevant data were retrieved from the final selected studies using a preconceived data-extraction form.

Results

A total of eight studies (three randomized-controlled trials, one prospective study, and four cross-sectional studies) were reviewed. A total of 6,243 participants were investigated in the eight studies and comprised young adults, middle-aged adults, and the elderly with a male-gender predominance. One randomized controlled trial reported that paricalcitol significantly improved renal function in type 1 diabetes patients with renal impairment when combined with renin-angiotensin-aldosterone system (RAAS) blockers. A strong correlation between vitamin D deficiency and DKD risk was noted in the majority of the cross-sectional studies. High doses of cholecalciferol (4,000 or 10,000 IU/day), given early in DKD, significantly reduced disease prevalence.

Conclusion

Paricalcitol may retard the onset or progression of DKD, especially if administered in combination with RAAS blockers. The association of vitamin D deficiency with DKD risk also supports this therapeutic effect. Future systematic reviews are still needed to strengthen the current evidence on therapeutic benefit of vitamin D or its analogs in DKD.

Trabecular bone score and 25-hydroxyvitamin D levels in microvascular complications of type 2 diabetes mellitus

BACKGROUND AND OBJECTIVE

Diabetic microvascular disease (MVD) has been associated with increased bone fragility. The objective was to analyse the relationship between MVD and trabecular microstructure -assessed by the trabecular bone score (TBS)- in type 2 diabetic (T2D) patients. A second aim was to know the relationship between vitamin D and MVD.

PATIENTS AND METHODS

Cross-sectional study, which included men >50 years and postmenopausal women participating in a population-based cohort, diagnosed with T2D. The presence of nephropathy, neuropathy and/or retinopathy was classified as MVD+. Clinical and laboratory variables, TBS, 25(OH)D and BMD by DXA, were evaluated. Bivariate and multivariate analysis were performed.

RESULTS

We evaluated 361 patients (51.1% women), 63.8 (9) years old. Of them, 92 were MVD+ and presented poorer metabolic control, longer duration of T2D, lower TBS [1.235 (.1) vs. 1.287 (.1); p=.007] and lower levels of 25(OH)D [18.3 (7) vs. 21.6 (8) ng/ml; p=.0001). There were no differences between MVD+ and MVD- with regard to BMD or P1NP and β-CTX markers. After adjusting for confounders, including HbA1c and duration of T2D, the TBS value in MVD+ was 1.252 (95% CI 1.230-1.274) vs. 1.281 (95% CI 1.267-1.295) in MVD- (p=.034). MVD was associated with a 25(OH)D level <20 ng ml with an adjusted OR of 1.88 (95% CI 1.06-3.31; p=.028).

CONCLUSIONS

The MVD+ patients presented a significantly lower TBS, after adjusting for confounders. Furthermore, multivariable analysis showed a significant relationship between a low 25(OH)D level and a prevalent MVD.

Association Between 25(OH)Vitamin D, HbA1c and Albuminuria in Diabetes Mellitus: Data From a Population-Based Study (VIDAMAZON)

BACKGROUND

The effect of glycemic control on diabetic kidney disease (DKD) is well known. Recent evidence has suggested that Vitamin D (VD) may have a nephroprotective effect in diabetes, but the relationship between VD, glycemic control, and albuminuria has yet to be clarified.

OBJECTIVE

Evaluate the relationship between 25-hydroxy-vitamin D [25(OH)D], HbA1c, and albuminuria in Diabetes Mellitus (DM).

PATIENTS AND METHODS

Cross-sectional study with 1576 individuals with DM who had 25(OH)D, HbA1c, and albuminuria levels measured. Patients with abnormal creatinine levels were excluded, in order to avoid interference on VD levels by impaired kidney function.

RESULTS

Patients with HbA1c ≥7% had lower 25(OH)D when compared to patients with HbA1c <7% (29.7 ± 10.2 vs 28.1 ± 9.9 ng/ml, p = 0.003) and 25(OH)D levels seems to predict 1.5% of HbA1c behavior. The 25(OH)D concentrations in patients with normoalbuminuria were higher than the levels observed in those with micro or macroalbuminuria (29.8 ± 9.0 vs 26.8 ± 8.6 and 25.1 ± 7.6, respectively, p = 0.001), patients who had 25(OH)D <20 ng/ml and 25(OH)D <30 ng/ml were at a higher risk of presenting albuminuria [OR = 2.8 (95% CI = 1.6 - 4.9), p<0.001, and OR = 2.1 (95% CI = 1.3 - 4.6), p<0.001, respectively]. In our regression model, albuminuria was influenced by HbA1c (r² = 0.076, p<0.00001) and 25(OH)D (r² = 0.018, p = 0.002) independently.

CONCLUSION

Our study found an association between vitamin D levels, HbA1c and DKD. Additionally, our data suggest that the association between urinary albumin excretion and vitamin D levels is independent of glycemic control in patients with diabetes. Even though our patients presented normal creatinine levels, it is necessary further prospective studies to confirm if this association precedes or not the loss of renal function.

A Nonlinear Relationship Between Serum 25-Hydroxyvitamin D and Urine Albumin to Creatinine Ratio in Type 2 Diabetes: A Cross-Sectional Study in China

BACKGROUND

Diabetic kidney disease often presents as increased urine albumin to creatinine ratio (UACR). 25-hydroxyvitamin D (25(OH)D) is considered as the best indicator of vitamin D status. Previous studies have shown that 25(OH)D is related to the UACR. However, evidence concerning the connection between 25(OH)D and UACR is still limited in the Chinese population.

MATERIALS AND METHODS

A total of 549 participants with type 2 diabetes were enrolled in the study from Shenzhen People's Hospital, China. The participants were grouped by the tertiles of 25(OH)D level. The association between 25(OH)D and UACR was examined by multiple linear regression. A generalized additive model (GAM) was used to verify a non-linear relationship. We conducted a subgroup analysis to evaluate the robustness of the results.

RESULTS

After adjusting for relevant variables, 25(OH)D was negatively correlated with UACR (β = -8.7, 95% CI (-12.0, -5.4)). A non-linear relationship was discovered between 25(OH)D and UACR, and the 25(OH)D threshold was 67. The effect sizes and confidence intervals on the left and right sides of the inflection point were -13.9 (-18.2, -9.6) and 8.9 (-1.1, 18.9), respectively. Subgroup analysis showed a stronger correlation could be detected in males. The same trend also could be found in patients older than 70 years old, those with using ACEI/ARB, with history of hypertension, with SBP ≥140 mmHg and eGFR <60 mL/min/1.73m².

CONCLUSION

The relationship between 25(OH)D and UACR is non-linear. 25(OH)D was negatively related to UACR when 25(OH)D is less than 67 nmol/L.

Association of vitamin D3 and its metabolites in patients with and without type 2 diabetes and their relationship to diabetes complications

Background

Epidemiological studies have suggested that vitamin D deficiency is associated with the development of type 2 diabetes (T2DM) and is related to diabetes complications. This study was undertaken to determine the relationship between diabetes complications and cardiovascular risk factors with vitamin D₃ and its metabolites: 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), 25-hydroxyvitamin D₃ (25(OH)D₃), 24,25-dihydroxyvitamin D₃ (24,25(OH)₂D₃); and 25-hydroxy-3epi-vitamin D₃ (3epi25(OH)D₃).

Methods

750 Qatari subjects, 460 (61.3%) with and 290 (38.7%) without T2DM, who were not taking vitamin D₃ supplements, participated in this cross-sectional, observational study. Plasma concentrations of vitamin D₃ and its metabolites were measured by liquid chromatography tandem mass spectrometry analysis.

Results

T2DM subjects had lower concentrations of all vitamin D₃ metabolites (p < 0.001) except 3epi25(OH)D₃ (p < 0.071). Males had higher concentrations of all vitamin D₃ metabolites (p < 0.001). In the T2DM subjects, lower 25(OH)D₃ was associated with retinopathy (p < 0.03) and dyslipidemia (p < 0.04), but not neuropathy or vascular complications; lower 1,25(OH)₂D₃ was associated with hypertension (p < 0.009), dyslipidemia (p < 0.003) and retinopathy (p < 0.006), and coronary artery disease (p < 0.012), but not neuropathy; lower 24,25(OH)₂D₃ concentrations were associated with dyslipidemia alone (p < 0.019); 3epi25(OH)D₃ associated with diabetic neuropathy alone (p < 0.029). In nondiabetics, 25(OH)D₃, 1,25(OH)₂D₃ and 24,25(OH)₂D₃ were associated with dyslipidemia (p < 0.001, p < 0.001, p < 0.015, respectively) and lower 1,25(OH)₂D₃ was associated with hypertension (p < 0.001). Spearman's correlation showed 1,25(OH)₂D₃ to be negatively correlated to age and diabetes duration.

Conclusions

Different diabetes complications were associated with differing vitamin D parameters, with diabetic retinopathy related to lower 25(OH)D₃ and 1,25(OH)₂D₃ levels, hypertension significantly associated with lower 1,25(OH)₂D₃, while dyslipidemia was associated with lower 25(OH)D₃, 1,25(OH)₂D₃ and 24,25(OH)₂D_3. While 25(OH)D metabolites were lower in females, there was not an exaggeration in complications.

Omega-3 fatty acids plus vitamin for women with gestational diabetes or prediabetes: a meta-analysis of randomized controlled studies

INTRODUCTION

Omega-3 fatty acids plus vitamin (e.g. vitamin D and E) may be beneficial to treat gestational diabetes mellitus (GDM), and we aimed to study the influence of omega-3 fatty acids plus vitamin versus placebo on the treatment efficacy of GDM.

METHODS

We searched the databases including PubMed, Embase, and the Cochrane Central Register of Controlled Trials, and randomized controlled trials (RCTs) assessing the influence of omega-3 fatty acids and vitamins combination supplementation versus placebo on metabolic status of GDM were included.

RESULTS

Five RCTs were included in the meta-analysis. Compared with control intervention for women with GDM or prediabetes, omega-3 fatty acids plus vitamin substantially reduced fasting plasma glucose (FPG, mean difference [MD] = -11.25; 95% confidence intervals [CI] = -13.73 to -8.77; p < .00001), insulin (MD=-6.16; 95% CI=-7.92 to -4.39; p < .00001), homeostasis model of assessment-insulin resistance (HOMA-IR, MD = 173.51; 95% CI = 164.72 to 182.30; p < .00001) and triglycerides (MD = 173.51; 95% CI = 164.72 to 182.30; p < .00001), as well as increased total antioxidant capacity (TAC, MD = 173.51; 95% CI = 164.72 to 182.30; p < .00001), but revealed no significant impact on total cholesterol (MD = 173.51; 95% CI = 164.72 to 182.30; p < .00001), low‑density lipoprotein cholesterol (LDL-C, MD = 173.51; 95% CI = 164.72 to 182.30; p < .00001), preterm delivery (OR = 173.51; 95% CI = 164.72 to 182.30; p < .00001) or macrosomia > 4000 g (OR = 173.51; 95% CI = 164.72 to 182.30; p < .00001).

CONCLUSIONS

The supplementation of omega-3 fatty acids in combination with vitamin D or E can improve glycemic control, alleviate oxidative stress, and reduce triglycerides, but had no effects on total cholesterol, preterm delivery or macrosomia > 4000 g in women with GDM or prediabetes.

Prevalence of Vitamin D Deficiency in Children with Type 1 Diabetes Mellitus

Background

In the recent years, controversy has emerged regarding the relationship between vitamin D deficiency and the potential effects it could have on glycemic control in patients with type 1 diabetes mellitus (T1D). This study investigates the prevalence of vitamin D insufficiency/deficiency in pediatric patients with T1D from a single, large volume practice.

Methods

This was a retrospective chart review that collected clinical/demographic data as well as serum 25(OH) D levels from medical records of 395 children between the ages of 3 and 18 years with T1D followed at Nemours Children’s Hospital. This data was compared to the National Health and Nutrition Examination Survey (NHANES) database. A Pearson’s Chi-square test was used between group associations. All statistical tests were two-sided and p < 0.05 was used for statistical significance.

Results

Of the 395 children included in these analyses, 4% were vitamin D deficient and 60% were vitamin D insufficient. There were no significant associations of vitamin D deficiency based on sex and age. Vitamin D deficiency was more common among White children when compared to Hispanic children and African American children (42% vs 29%; p < 0.001). Of those that were vitamin D insufficient (n = 235), most were Hispanic (51%), 36% White and 13% African American. There was a significant association between vitamin D deficiency and body mass index (BMI) (p = 0.035). In the summer, children were less likely to be vitamin D deficient (3% vs 6% in winter) and less likely to be vitamin D insufficient (55% vs 71% in winter) (p = 0.007).

Conclusions

Vitamin D insufficiency is highly prevalent among pediatric type 1 diabetics of Central Florida and statistically significant correlation was found between vitamin D status and ethnicity, BMI as well as seasonal variation.

Vitamin D status in Israeli pediatric type 1 diabetes patients: the AWeSoMe Study Group experience and literature review

Background The prevalence of both vitamin D (VitD) deficiency and type 1 diabetes mellitus (T1DM) has increased worldwide over the last few decades. The objectives of this study were: (1) to evaluate the prevalence of VitD deficiency and insufficiency among Israeli youth with T1DM and (2) to assess the association between VitD status, seasonality and T1D glycemic control characteristics. Methods This was a multi-centered, cross-sectional study. VitD levels were routinely tested during the years 2008-2011 in T1DM patients aged up to 21 years. Medical records were reviewed for demographic, clinical and laboratory characteristics. Results The study population consisted of 199 participants (53% males), mean age 12.24±4.11 years, mean T1DM duration 3.77±3.43 years. VitD levels were within the normal range in 19.6%, insufficient (15-29 ng/mL, 37-72 nmol/L) in 62.3% and deficient (<15 ng/mL, <37 nmol/L) in 18.1%. Mean VitD level was higher during the summer than during spring, autumn and winter (28.65 ng/mL, 23.16 ng/mL, 21.65 ng/mL, 17.55 ng/mL, respectively, p<0.001). Mean VitD level was higher among secular patients compared to the religious (whole-year heavily dressed) population (23.57 ng/mL, 15.54 ng/mL, respectively, p<0.001). VitD level was negatively associated with body mass index calculation of standard deviation scores (BMI-SDS), high-density lipoprotein (HDL) and age at diagnosis (r=-0.171, p=0.016; r=-0.149, p=0.043; r=-0.150, p=0.037, respectively). No association was demonstrated with disease duration and glycemic control indices and metabolic parameters. Conclusions VitD insufficiency is largely prevalent among Israeli youth with T1DM, as is in Israeli youth in general. The VitD level is associated with seasonality, clothing habits and BMI.

The effect of omega-3 and vitamin D co-supplementation on glycemic control and lipid profiles in reproductive-aged women with pre-diabetes and hypovitaminosis D: a randomized controlled trial

BACKGROUND

Prediabetes can predispose the individual to type 2 diabetes in the long-term. The present study was conducted to determine the effectiveness of vitamin D and omega-3 co-supplementation on glycemic control and serum lipid profiles in women of reproductive age with prediabetes and hypovitaminosis D.

METHODS

The present factorial, triple-blind, clinical trial was conducted on 168 women of reproductive age with prediabetes and hypovitaminosis D. The participants were assigned to four groups based on block randomization method: the placebo group received omega-3 and vitamin D placebos; the omega-3 group took omega-3 supplements and vitamin D placebos; the vitamin D group received omega-3 placebos and vitamin D supplements and the co-supplementation group. The groups received every 2 weeks 50,000 IU pearls of vitamin D and twice-daily doses of 1000-mg omega-3 tablets or placebos for 8 weeks. Dietary intake, physical activity, anthropometric indices and blood biochemical tests were measured at the beginning and end of the study. Analysis was performed using two-way mixed ANOVA.

RESULTS

A significant reduction was observed in fasting glucose, insulin, homeostasis model assessment-beta cell function, weight and waist circumference in the co-supplementation group compared to the other three groups (P < 0.05). Moreover, high-density lipoprotein-cholesterol levels increased significantly in the co-supplementation group compared to the other three groups (P < 0.05). Despite the fact that homeostasis model assessment-insulin resistance, total cholesterol, triglyceride and low-density lipoprotein-cholesterol levels decreased after intervention in the co-supplementation group, there was no significant difference between the groups in these outcomes.

CONCLUSION

Vitamin D and omega-3 co-supplementation improved fasting serum glucose, insulin, high-density lipoprotein-cholesterol level, homeostasis model assessment-beta cell function, weight and waist circumference in women of reproductive age with prediabetes and hypovitaminosis D. This co-supplementation can therefore be recommended for glycemic control in these women.Trial registration Iranian Registry of Clinical Trials Code: IRCT20100130003226N17. Registered on 9 Feb. 2019.

Predictors of future microalbuminuria in children and adolescents with type 1 diabetes mellitus in Egypt

Introduction

The present study was designed to assess the validity and efficacy of urinary markers (NAG, RBP, transferrin, α1-microglobulin, and plasma homocysteine) as early predictors of microalbuminuria in diabetic nephropathy in children and adolescents with type-1 diabetes, and its relation with haemoglobin glycated (HbA_1c), serum lipid profile, and blood pressure.

Material and methods

This study is a follow-up study to the 2002 study by Salem et al. The present study included 35 type 1 diabetes mellitus (T1DM) children and adolescents recruited from regular attendees of the specialised Diabetology Clinic, Children’s hospital, Ain Shams University, with previously measured urinary N-acetyl-β-glucosaminidase (13) or homocysteine (11) or transferrin (28) or α1-microglobulin (27) or retinol binding protein (13) as an early predictor of diabetic nephropathy in T1DM. Thirty-five patients with type 1 diabetes mellitus were enrolled, and 24 patients were normoalbuminuric at baseline. The patients were tested for markers other than urinary microalbumin, to predict diabetic nephropathy and early renal impairment in children and adolescents with type 1 diabetes mellitus.

Results

Regarding the metabolic control between the studied groups, we found that there is significant difference in HbA_1c between the microalbuminuric patients and the normoalbuminuric patients. According to the number of positive markers of diabetic nephropathy, the only parameter that was higher in patients with more than one elevated marker was mean systolic blood pressure. Although mean diabetic blood pressure was higher, it was not statistically significant. Regarding to the predictability of urinary markers, urinary N-acetyl-β-glucosaminidase is the most predictable marker with high sensitivity and specificity. The least sensitivity noticed was urinary RBP and the least specificity noticed was urinary α1-microglobulin.

Conclusions

Regarding the predictability of urinary markers, urinary NAG is the most predictable marker with both high sensitivity and specificity, with a sensitivity of 60%, specificity 75%, positive predictive value 60%, negative predictive value 75%, and a diagnostic accuracy of 0.58%. Urinary RBP is another marker with low sensitivity but high specificity. Urinary α1-microglobulin is a valid marker with high sensitivity but low specificity. Contrary to previous markers, plasma homocysteine has high specificity but low sensitivity.

Vitamin D status among adults (18-65 years old) attending primary healthcare centres in Qatar: a cross-sectional analysis of the Electronic Medical Records for the year 2017

OBJECTIVES

To investigate the prevalence of vitamin D deficiency among individuals attending primary healthcare facilities in Qatar and to assess the association between vitamin D deficiency and some medical conditions in persons aged 18-65 years old.

SETTING

The study was undertaken in publicly funded primary healthcare services in the State of Qatar.

PARTICIPANTS

A total of 102 342 participants aged between 18 and 65 years old with a valid serum vitamin D test result during the year 2017.

OUTCOME MEASURES

Serum level <10 ng/mL (<25 nmol/L) was defined as severe vitamin D deficiency, a serum level of <20 ng/mL (<50 nmol/L) was defined as vitamin D deficiency and a serum level <30 ng/mL (<75 nmol/L) defined as vitamin D insufficiency.

RESULTS

The prevalence rate of severe vitamin D deficiency was 14.1% among study participants with no history of vitamin D replacement therapy in the previous months. The prevalence rate of vitamin D deficiency was as high as 71.4% and that of vitamin D insufficiency was up to 92.7%. None of the five chronic conditions explored in the study (diabetes, hypertension, asthma, stroke and cardiovascular disease) had an obvious association with severe vitamin D deficiency status in a bivariate analysis. However, multivariate modelling showed that (adjusting for age, gender, body mass index and nationality and each of the included chronic conditions) hypertension, cardiovascular diseases and stroke placed an individual at a higher risk of having an associated severe vitamin D deficiency status.

CONCLUSION

Although not comprehensive and nationally representative, this study is suggestive of a higher prevalence of vitamin D deficiency among young adults, females, Qatari nationality and those with higher body mass index. Multivariate modelling showed that hypertension, cardiovascular diseases and stroke were associated with a higher risk of severe vitamin D deficiency status.

Evaluation of the relationship between microalbuminuria and 25-(OH) vitamin D levels in patients with type 2 diabetes mellitus

BACKGROUND

25-(OH) vitamin D (VD) deficiency has been described as potential risk factor for the development of diabetes in many epidemiological studies. 25-(OH) VD deficiency and insulin resistance associated with this deficiency are common findings in patients with type 2 diabetes mellitus. The objective of this study is to evaluate the relationship between 25-(OH) VD levels and microalbuminuria.

METHODS

The patients with type 2 diabetes mellitus aged between 40 and 65 years, who were admitted to the diabetes outpatient clinics of our hospital, were evaluated in two different groups. The first group consisted of 119 patients with insufficient 25-(OH) VD levels (10-30 ng/mL) and the second group consisted of 121 patients with 25-(OH) VD deficiency (≤10 ng/mL). The relationship between 25-(OH) VD levels and the level of microalbuminuria was evaluated in the two groups.

RESULTS

The mean 25-(OH) VD level was 11.5 ng/mL and the mean HbA1c level was 9.1%. When the patient groups were evaluated according to 25-(OH) VD levels, HbA1c values were significantly higher in patients with a 25-(OH) VD level of 10 ng/mL or lower (p = .039). 25-(OH) VD levels were not significantly different between patients with different stages of renal failure (p = .119), whereas the level of microalbuminuria was significantly different (p = .030).

CONCLUSIONS

This study found that the level of microalbuminuria was significantly higher in patients with 25-(OH) vitamin D deficiency compared to patients with 25-(OH) VD insufficiency.

Association between serum 25-hydroxyvitamin D and diabetic kidney disease in Chinese patients with type 2 diabetes

Objective

The objective was to assess the association between 25-hydroxyvitamin D (25OHD) level and diabetic kidney disease (DKD) in Chinese patients with type 2 diabetes.

Methods

Data pertaining to 351 in-patients with type 2 diabetes were collected. Subjects were classified into three groups based on the level of urinary albumin-to-creatinine ratio (UACR). UACR < 30 mg/g was defined as normoalbuminuria, while UACR levels of 30–300 mg/g and ≥ 300 mg/g were defined as microalbuminuria and macroalbuminuria, respectively. Serum 25OHD and other clinical characteristics among various UACR groups were compared. The relationship between albuminuiria and 25OHD was analyzed.

Results

The prevalence of 25OHD insufficiency in the microalbuminuria group was significantly higher than that in the normoalbuminuria group (25.1% vs. 19.6%; P < 0.05); patients with macroalbuminuria had the highest prevalence of 25OHD deficiency (37.8%; P < 0.01 versus normoalbuminuria). Logistic regression analyses demonstrated that low 25OHD levels were associated with DKD [odds ratio (OR) = 1.51, 95% confidence interval (CI) 1.16–1.97). The association was more robust after adjusting for sex, hypertension, increased systolic blood pressure, glycemic status, and hyperuricemia (OR = 1.62, 95% CI 1.19–2.20).

Conclusions

The prevalence of vitamin D insufficiency/deficiency in patients with albuminuria was overtly higher than that in patients without albuminuria among Chinese adults with type 2 diabetes. Vitamin D insufficiency/deficiency was independently associated with DKD in type 2 diabetes.

Vitamin D Deficiency in Chronic Kidney Disease: Recent Evidence and Controversies

Vitamin D (VD) is a pro-hormone essential for life in higher animals. It is present in few types of foods and is produced endogenously in the skin by a photochemical reaction. The final step of VD activation occurs in the kidneys involving a second hydroxylation reaction to generate the biologically active metabolite 1,25(OH)₂-VD. Extrarenal 1α-hydroxylation has also been described to have an important role in autocrine and paracrine signaling. Vitamin D deficiency (VDD) has been in the spotlight as a major public healthcare issue with an estimated prevalence of more than a billion people worldwide. Among individuals with chronic kidney disease (CKD), VDD prevalence has been reported to be as high as 80%. Classically, VD plays a pivotal role in calcium and phosphorus homeostasis. Nevertheless, there is a growing body of evidence supporting the importance of VD in many vital non-skeletal biological processes such as endothelial function, renin-angiotensin-aldosterone system modulation, redox balance and innate and adaptive immunity. In individuals with CKD, VDD has been associated with albuminuria, faster progression of kidney disease and increased all-cause mortality. Recent guidelines support VD supplementation in CKD based on extrapolation from cohorts conducted in the general population. In this review, we discuss new insights on the multifactorial pathophysiology of VDD in CKD as well as how it may negatively modulate different organs and systems. We also critically review the latest evidence and controversies of VD monitoring and supplementation in CKD patients.

Vitamin D Supplementation, Glycemic Control, and Insulin Resistance in Prediabetics: A Meta-Analysis

Diabetes prevention is a public health priority. Vitamin D supplementation may help prevent the development of diabetes in persons at increased risk. We performed a meta-analysis of controlled clinical trials that assessed glycemic outcome measures among adults at risk for type 2 diabetes, including prediabetes, overweight, or obesity. We searched PUBMED/ MEDLINE, CINAHL, and Google Scholar databases for trials published prior to April 2017. Placebo-controlled clinical trials with random allocation to vitamin D with or without calcium supplementation were selected. Data collection included country, study design, inclusion criteria, sample size, form, and dose of vitamin D, supplementation interval, control group, duration, participant characteristics, comorbidities, baseline and follow-up serum 25-hydroxyvitamin D [25(OH)D] concentration, and available outcome measures [glycosylated hemoglobin (HbA1c), fasting plasma glucose, plasma glucose after 2-hour oral glucose tolerance test, and homeostatic model assessment of insulin resistance (HOMA-IR)]. Data synthesis was conducted using random-effect models (PROSPERO registration no. CRD42017055326). Twenty-eight trials, representing 3848 participants, met the eligibility criteria. Compared with the control group, vitamin D supplementation significantly reduced HbA1c level by -0.48% (95% CI, -0.79 to -0.18), fasting plasma glucose level by -0.46 mmol/L (95% CI, -0.74 to -0.19), and HOMA-IR level by -0.39 (95% CI, -0.68 to -0.11). Subgroup analysis revealed that the effects of vitamin D supplementation on different glycemic measures were influenced by age, calcium coadministration, vitamin D deficiency, serum 25(OH)D level after supplementation, and duration of supplementation. Vitamin D supplementation and improved vitamin D status improved glycemic measures and insulin sensitivity and may be useful as part of a preventive strategy for type 2 diabetes.

Association of serum vitamin D levels and diabetic retinopathy in Asian Indians with type 2 diabetes

BACKGROUND

Vitamin D deficiency (VDD) is a condition that has been associated with diabetic retinopathy (DR) in various populations, but has not been studied in Asian Indians.

AIMS

To evaluate the association of serum 25-hydroxyvitamin D (25(OH)D) levels with presence and severity of DR among Asian Indians with type 2 diabetes.

METHODS

We collected information on individuals with type 2 diabetes that received care at a tertiary diabetes centre in India, between 2012 and 2015. Patients were 18 years of age or older, underwent retinal examinations with DR severity grading and had serum 25(OH)D measurements.

RESULTS

Serum 25(OH)D levels were lower in patients with retinopathy compared to those without (11.9 ± 2.2 ng/ml vs. 13.7 ± 2.1 ng/ml, p < 0.001). Stratifying patients by DR grade, reduced geometric means of 25(OH)D levels were associated with increased retinopathy severity. After adjusting for six key covariates, VDD was associated with increased rates of proliferative DR (OR 2.05; 95% CI 1.35-3.11; p = 0.001).

CONCLUSIONS

In Asian Indians with type 2 diabetes, lower serum 25(OH)D was associated with increased severity of DR and the presence of VDD was associated with a two-fold increased risk for proliferative DR.

Improvements in peripheral vascular function with vitamin D treatment in deficient adolescents with type 1 diabetes

BACKGROUND

Vitamin D (VitD) deficiency is prevalent in adolescents with type 1 diabetes (T1D) and is associated with diabetes-related vascular complications in adulthood. The objective of this clinical trial was to assess VitD treatment on endothelial function (EF) and markers of renal inflammation, in this patient group.

METHODS

Adolescents with T1D with suboptimal levels of VitD (<37.5 nmol/L) were treated for 12 to 24 weeks with a VitD analog (VitD₃ ) at doses of 1000 or 2000 IU daily. The primary end-point assessed the change in reactive hyperemia index (lnRHI), a measure of EF. Secondary end-points included changes in blood pressure, lipid profile, HbA1c and albumin creatinine ratio (ACR). Urinary cytokine/chemokine inflammatory profile was also assessed in a subset of subjects posttreatment.

RESULTS

Two hundred and seventy-one subjects were screened for VitD status and 31 VitD deficient subjects with a mean age of 15.7 ± 1.4 years were enrolled and completed the study. Mean 25-OH-VitD levels significantly increased (33.0 ± 12.8 vs 67.0 ± 23.2 nmol/L, P < .01) with a significant improvement in EF following VitD supplementation (lnRHI 0.58 ± 0.20 vs 0.68 ± 0.21, P = .03). VitD supplementation did not significantly impact systolic blood pressure/diastolic blood pressure (SBP/DBP), lipids, HbA1c and ACR and no adverse effects were seen. Several urinary inflammatory cytokines/chemokines: MCP-3 (P < .01), epidermal growth factor (EGF) (P < .01) tumor necrosis factor β (TNFβ) (P = .01), interleukin-10 (IL-10) (P = .01), also significantly decreased post-VitD-treatment.

CONCLUSIONS

Treatment with VitD was associated with an improvement in EF and reduced expression of urinary inflammatory markers in adolescents with T1D. This data is suggestive of an additional benefit of VitD supplementation on early markers of microvascular complications.

Parenteral vitamin D supplementation is superior to oral in vitamin D insufficient patients with type 2 diabetes mellitus

BACKGROUND/OBJECTIVES

Oral vitamin D supplementation is better than parenteral in improving vitamin D deficiency in individuals with no systemic illness. Our aim was to compare the efficacy of oral and parenteral routes of vitamin D supplementation on circulating serum 25(OH) vitamin D level in patients with type 2 diabetes mellitus.

METHODS

Total 85 cases of with type 2 diabetes mellitus were screened for vitamin D status of which 71 patients were vitamin D insufficient/deficient. They were randomized into two intent to treat groups with different vitamin D supplementation protocols (a) Oral-60000 IU per day for 5days (group I; n=40) and (b) injectable-300000 IU intramuscularly once (group II; n=31). Baseline and one month post supplementation 25(OH) vitamin D levels were measured in both the groups.

RESULTS

Baseline clinical characteristics and 25(OH) vitamin D levels were comparable in both the groups. Post treatment 25(OH) vitamin D level in group I was 26.06±9.06ng/ml and in group II was 49.69±18.92ng/ml. After one month of vitamin D supplementation, increment in 25(OH) vitamin D level from baseline was significantly higher in group II than group I (p<0.001).

INTERPRETATION & CONCLUSIONS

Injectable method of supplementation was better than oral route in improving serum 25 (OH) vitamin D status in patients with type 2 diabetes. The study suggested impaired absorption of vitamin D from the gastrointestinal tract in patients with type 2 diabetes mellitus and a need for parenteral route of vitamin D supplementation in deficient patients with type 2 diabetes mellitus.

Vitamin D levels in subjects with or without chronic kidney disease among Veterans with diabetes in North East United States

AIM

To evaluate the prevalence of vitamin D deficiency and its relation to diabetes and kidney disease in Veterans residing in the North East United States (VISN 2).

METHODS

In this retrospective study, we used data from the computerized patient record system at Stratton Veterans Administration Medical Center at Albany, NY (VHA) for those patients who had 25-hydroxyvitamin D levels and 1,25 (OH) vitamin D levels measured between 2007 and 2010. We collected demographic information including age, sex, body mass index and race; clinical data including diabetes, hypertension and CAD; and laboratory data including calcium, creatinine and parathyroid hormone (PTH) (intact). Vitamin D deficiency is defined as a serum 25-hydroxyvitamin D level of less than 20 ng/mL (50 nmol/L), and insufficiency is defined as a serum 25-hydroxyvitamin D level of 20 to 30 ng/mL (50 to 75 nmol/L).

RESULTS

Data was available for approximately 68000 subjects. We identified 64144 subjects for analysis after exclusion of duplicates. Among them, 27098 had diabetes. The mean age of subjects with diabetes was 68 ± 11 with a mean body mass index (BMI) of 32 ± 7 and duration of diabetes of 5.6 ± 3.2 years. The mean 25 (OH) vitamin D level among subjects with diabetes was 27 ± 11.6. There was no significant difference in 25 (OH) vitamin D levels between subjects with diabetes and glomerular filtration rate (e-GFR) < 60 compared to those with e-GFR ≥ 60. As expected, subjects with e-GFR < 60 had significantly lower 1,25 (OH) vitamin D levels and significantly elevated PTH-intact. Of the 64144 subjects, 580 had end-stage renal disease. Of those, 407 had diabetes and 173 did not. Vitamin D levels in both groups were in the insufficiency range and there was no significant difference irrespective of presence or absence of diabetes. Subjects with vitamin D levels less than 20 ng/mL had a higher BMI and elevated PTH, and higher HbA1C levels compared to those with vitamin D levels more than 20 ng/mL.

CONCLUSION

We conclude that we need to keep a close eye on vitamin D levels in subjects with mild chronic kidney disease as well as those with moderate control of diabetes.

Glycated hemoglobin A1C and vitamin D and their association with diabetic retinopathy severity

OBJECTIVES

This retrospective, population-based, cross-sectional study evaluated the association between vitamin D deficiency and retinopathy severity in diabetic patients with poorly or well controlled glycaemia. Other potential risk factors for diabetic retinopathy severity were also assessed.

METHODS

The National Health and Nutrition Examination Survey (NHANES) 2005-2008 data were used for the study. Outcomes assessed included retinopathy severity, HbA1c levels, socioeconomic, behavioral, and biological factors. Univariate and multivariate regression analysis was used to evaluate association of different parameters with retinopathy severity. The interaction among HbA1c control, vitamin D deficiency, and retinopathy severity were also explored.

RESULTS

The population included 842 adults (52.8% women) with mean age of 61.2 years. Retinopathy was detected in 301 subjects (35.7%). Mild non-proliferative retinopathy (NPR) was present in 195 subjects (23.2%), severe non-proliferative and proliferative retinopathy in 106 subjects (12.6%). Multivariate ordinal regression analysis found being male (odds ratio (OR): 1.602, P=0.001), increased duration of diabetes (OR: 1.072, P=3.77E-7) and poorly controlled HbA1c (OR: 3.522, P=2.00E-5) were associated with greater retinopathy severity. The association between vitamin D deficiency and retinopathy severity only found in diabetic patients with well controlled glycaemia.

CONCLUSIONS

The findings of this study indicate that vitamin D deficiency associated with severe diabetic retinopathy in patients with well controlled diabetes. The findings provide possible relationship for the previous conflict results, and highlight the need for controlling modifiable risk factors to reduce the development of sever diabetic retinopathy.

Vitamin D and Albuminuria in Youth with and without Type 1 Diabetes

BACKGROUND/AIMS

In adults, lower vitamin D has been associated with increased albuminuria. This association has not been extensively studied in youth with or without type 1 diabetes.

METHODS

We examined the cross-sectional association between vitamin D and albuminuria (urine albumin to creatinine ratio ≥30 mg/g) in 8,789 participants of the National Health and Nutrition Survey 2001-2006 (NHANES), who were 6-19 years old. Further, we examined the association between vitamin D and albuminuria in 938 participants from the SEARCH Nutritional Ancillary Study (SNAS), a longitudinal cohort of youth with type 1 diabetes.

RESULTS

Of the NHANES participants, 5.3, 19.5, and 53.7% had vitamin D levels <30, 50 and 80 nmol/L, respectively. Albuminuria was present in 12.8% and was more common in younger children, females, non-Hispanic whites, non-obese children, and children with hypertension. After adjustments, there was no association between vitamin D and albuminuria. Among the SNAS participants with type 1 diabetes, we also found no association between baseline vitamin D and subsequent albuminuria in unadjusted or adjusted analyses.

CONCLUSION

We did not find an association between serum vitamin D and albuminuria in either non-diabetic youth or those with type 1 diabetes. Further research is needed to more fully understand this relationship.

Clinical, behavioural and social indicators for poor glycaemic control around the time of transfer to adult care: a longitudinal study of 126 young people with diabetes

AIMS

To describe and compare changes in glycaemic control in young people with Type 1 diabetes over time between the last 2 years in paediatric care and the first 2 years in adult care and to identify risk factors for poor glycaemic control.

METHODS

Our retrospective cohort study followed participants aged 14-22 years from 2 years before to 2 years after transfer from paediatric to adult care. Changes in glycaemic control were calculated using repeated measurements. We adjusted for gender, age at diabetes onset, age at transfer, duration of diabetes at transfer, gap (amount of time) between last paediatric and first adult visit, comorbidity, learning disability and/or mental health conditions and family structure. We examined associations between acute hospital admissions, low visit attendance rate, loss to follow-up and baseline HbA_1c level.

RESULTS

Among 126 participants, the mean HbA_1c level was 80 mmol/mol (9.4%) pre-transfer but decreased by an average of 3 mmol/mol (0.3%) each year post-transfer (P = 0.005). Young people with a learning disability and/or a mental health condition had worse glycaemic control (P = 0.041) and the mean HbA_1c of those with divorced parents was 14 mmol/mol (1.2%) higher (P = 0.014). Almost one-third of participants were admitted to the hospital for acute diabetes care. Low visit attendance rate, high baseline HbA_1c level, learning disability and/or mental health conditions and divorced parents predicted acute hospital admissions.

CONCLUSIONS

Glycaemic control improved significantly after transfer to adult care, but the mean HbA_1c level remained high. Future interventions should focus on young people with divorced parents, those with a learning disability and/or mental health condition and those who do not attend clinical visits to improve HbA_1c levels and thereby reduce hospitalization rates.

Vitamin D on Early Stages of Diabetic Kidney Disease: A Cross-sectional Study in Patients with Type 1 Diabetes Mellitus

CONTEXT

Genetic and environmental factors are involved in the pathogenesis of type 1 diabetes mellitus (T1DM), and vitamin D (VD) deficiency appears as a candidate to risk factor for developing diabetic kidney disease (DKD).

OBJECTIVE

The purpose of study was to evaluate the existence of an association between low levels of VD and the presence and degree of DKD in T1DM.

PATIENTS AND METHODS

We performed a cross-sectional study, between November 2014 and December 2015. Levels of 25(OH)D and albuminuria were analyzed in 37 patients with T1DM and normal glomerular filtration rate. Thirty-six subjects were evaluated as a control group.

RESULTS

Patients with T1DM and hypovitaminosis D had higher levels of albuminuria compared to those with normal VD levels [albuminuria (log10) = 1.92 vs. 1.44; p < 0.05]. When we have separated the group of patients according to stage of DKD in patients with normo, micro, and macroalbuminuria, there are lower levels of 25(OH)D in the last when compared to the first two groups (26.7 ± 6.2, 24.8 ± 7.0, and 15.9 ± 7.6 ng/ml; p < 0.05, respectively). In T1DM group, we have found correlations between VD levels and both albuminuria and DKD stages (r = -0.5; p < 0.01 and r = -0.4; p < 0.05, respectively). A simple linear regression model, with albuminuria as the dependent variable and VD as an independent variable, showed r2 = 0.2 and p < 0.01.

CONCLUSION

Our data suggest an association between reduced levels of VD and the presence and severity of DKD.

Vitamin D status in youth with type 1 and type 2 diabetes enrolled in the Pediatric Diabetes Consortium (PDC) is not worse than in youth without diabetes

OBJECTIVE

To describe vitamin D levels and prevalence of vitamin D sufficiency, insufficiency and deficiency in a large, ethnically/racially diverse population of youth with type 1 diabetes (T1D) and type 2 diabetes (T2D) in comparison to national data and examine the associations between clinical/demographic factors and vitamin D levels.

METHODS

25-hydroxy vitamin D (25OHD) levels were measured in 215 youth with T1D and 326 youth with T2D enrolled in the Pediatric Diabetes Consortium (PDC). These levels were compared with those of youth of the same age without diabetes from the 2005-2006 NHANES Survey.

RESULTS

Vitamin D deficiency (<21 ng/mL) was present in 36% of PDC participants, and insufficiency (21-29 ng/mL) was present in an additional 34%. About 36% of age-matched youth in the NHANES Survey were vitamin D deficient and an additional 41% were insufficient. Deficiency or insufficiency varied by race/ethnicity, being highest in African-Americans (86%), intermediate in Hispanics (77%), and lowest in non-Hispanic whites (47%). Lower 25OHD levels were observed in African-American and Hispanic youth, during fall and winter, and at sites in the northern United States (all p-values < 0.001). Youth with T2D had significantly lower 25OHD levels than youth with T1D (p < 0.001), but this difference was largely eliminated after adjusting for race/ethnicity and socio-economic status.

CONCLUSIONS

Vitamin D deficiency/insufficiency is present in a substantial proportion of youth with diabetes, particularly minorities, but the prevalence appears similar to that in youth without diabetes. Further studies are needed to examine whether youth with diabetes would benefit from vitamin D supplementation.

Consumption of Dietary Resistant Starch Partially Corrected the Growth Pattern Despite Hyperglycemia and Compromised Kidney Function in Streptozotocin-Induced Diabetic Rats

We previously demonstrated that feeding of dietary resistant starch (RS) prior to the induction of diabetes delayed the progression of diabetic nephropathy and maintained vitamin D balance in streptozotocin (STZ)-induced type 1 diabetic (T1D) rats. Here, we examined the impact of RS on kidney function and vitamin D homeostasis following STZ injection. Male Sprague-Dawley rats were administered STZ and fed a standard diet containing cornstarch or 20, 10, or 5% RS for 4 weeks. T1D rats fed 10 and 20% RS, but not 5% RS, gained more weight than cornstarch-fed rats. Yet, renal health and glucose metabolism were not improved by RS. Our data suggest that RS normalized growth patterns in T1D rats after diabetes induction in a dose-dependent manner despite having no effect on blood glucose and vitamin D balances. Future interventions should focus on the preventative strategies with RS in T1D.

Adequate vitamin D status is associated with the reduced odds of prevalent diabetic retinopathy in African Americans and Caucasians

BACKGROUND

Vitamin D status has been hypothesized to protect against development of diabetic retinopathy via its anti-inflammatory and anti-angiogenic properties. Additionally, in vitro and in vivo studies suggest vitamin D favorably influences blood pressure and blood glucose control, strong risk factors for diabetic retinopathy. We examined the association between vitamin D status and prevalent diabetic retinopathy in participants with diabetes from a population-based cohort.

METHODS

Among participants in the Atherosclerosis Risk in Communities (ARIC) study with diabetes at visit 3 (1993-1995), 1339 (906 Caucasians, 433 African Americans) had serum 25-hydroxyvitamin (25[OH]D) concentrations assessed at visit 2 (1989-1992) and nonmydriatic retinal photographs taken at visit 3. Dietary intake of vitamin D was assessed at visit 1 (1987-1989). Logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs) for diabetic retinopathy by categories of season-adjusted 25(OH)D (<30 [referent], 30-<50, 50-<75 and ≥75 nmol/L), by quartile of vitamin D intake (IU/day), and use of vitamin D or fish oil supplements (yes/no). P for trend was estimated using continuous 25(OH)D or vitamin D intake. ORs were adjusted for race, and duration of diabetes. We further adjusted for HBA1c and hypertension to examine if 25(OH)D influenced diabetic retinopathy via its effects on either glycemic control or blood pressure.

RESULTS

ORs (95 % CIs) for retinopathy, adjusted for race and duration, were 0.77 (0.45-1.32), 0.64 (0.37-1.10), and 0.39 (0.20-0.75), p for trend = 0.001, for participants with 25(OH)D of 30-<50, 50-<75, and ≥75 nmol/L, respectively. Further adjustment for hypertension minimally influenced results (data not show), but adjustment for HBA1c attenuated the OR among those with 25(OH)D ≥75 (0.47 [0.23-0.96], p for trend = 0.030). No statistically significant association was observed between vitamin D intake from foods or supplements and retinopathy.

CONCLUSIONS

25(OH)D concentrations ≥75 nmol/L were associated with lower odds of any retinopathy assessed 3 years later. We speculate this may be due in part to vitamin D's influence on blood glucose control.

Vitamin D and extra-skeletal health: causality or consequence

Vitamin D deficiency /insufficiency is widely recognized as a global health problem that is likely to be involved in pathogenesis or progression of many acute and chronic health disorders. Its relation to skeletal health has been clearly demonstrated and thoroughly examined. This review aims to highlight the continuous debate about the relation between vitamin D and extra-skeletal health and whether it is a causality or just an association. Overall, the available evidence does not meet the criteria for establishing cause-and-effect relationships because of the limitations of observational studies to corroborate the causality due to many potential confounders. Moreover, the causal relationship couldn't be established in randomized studies or in many meta-analyses. This may reflect the fact that vitamin D level reduction is just a biomarker of ill health. The inflammatory processes involved in the disease occurrence and the functional limitations of the diseases would have a role in reducing serum 25-hydroxy vitamin D "25 (OH) D" level, which would explain why low vitamin D is reported in a wide range of disorders. This may underscore the possibility of harm instead of benefit of vitamin D supplementation when its exact role is not fully established, thus many guidelines and interest groups are still hesitant toward recommending replacement in extra-skeletal disease. Future directions entails the need for a large well-designed randomized control trials (RCTs) to resolve the active debate on the benefits of vitamin D replacement for extra-skeletal disease, and not only that, future studies should establish specific, clinically relevant effects of vitamin D repletion, provide cut-values for optimal serum levels of 25 (OH) D, and appropriate doses for non-skeletal health benefits.

25-Hydroxyvitamin D and glycemic control: A cross-sectional study of children and adolescents with type 1 diabetes

AIM

The objective of this study was to describe the vitamin D status of children and adolescents with type 1 diabetes and to evaluate whether levels of 25-hydroxyvitamin D are significantly associated with HbA1c in this population.

METHODS

197 children and adolescents from a diabetes center in a children's hospital were recruited during regular follow up visit. Non-fasting blood samples were collected to measure 25-hydroxyvitamin D and blood glucose levels. HbA1c and other key variables were abstracted from patients' medical records.

RESULTS

Of the 197 children and adolescents, more than half were adolescents, males, and Caucasian. 23% were overweight, while 13% were obese. Mean HbA1c was 8.6±1.4% (70±15.3mmol/mol). 40.6% of patients had 25-hydroxyvitamin D levels ≤50nmol/L; 49.2% had 25-hydroxyvitamin D levels between 51 and 75nmol/L and 10.2% had 25-hydroxyvitamin D levels >75nmol/L. The bivariate relationship between 25-hydroxyvitamin D and HbA1c almost reached statistical significance (P=0.057), while no significance was established in the multivariate model.

CONCLUSIONS

To the best of our knowledge this is the first study that has been adequately-powered to examine the association between 25-hydroxyvitamin D and HbA1c in children and adolescents with T1DM. This study demonstrated the high prevalence of patients with low levels of 25-hydroxyvitamin D specifically in healthy weight and Caucasian children and adolescents with T1DM. These data suggest the need for monitoring of 25-hydroxyvitamin D in all youth with T1DM.

Assessing vitamin D nutritional status: Is capillary blood adequate?

BACKGROUND

Venous blood is the usual sample for measuring various biomarkers, including 25-hydroxyvitamin D (25OHD). However, it can prove challenging in infants and young children. Hence the finger-prick capillary collection is an alternative, being a relatively simple procedure perceived to be less invasive. We elected to validate the use of capillary blood sampling for 25OHD quantification by liquid chromatography tandem-mass spectrometry (LC/MS-MS).

METHODS

Venous and capillary blood samples were simultaneously collected from 15 preschool-aged children with asthma 10days after receiving 100,000IU of vitamin-D3 or placebo and 20 apparently healthy adult volunteers. 25OHD was measured by an in-house LC/MS-MS method.

RESULTS

The venous 25OHD values varied between 23 and 255nmol/l. The venous and capillary blood total 25OHD concentrations highly correlated (r(2)=0.9963). The mean difference (bias) of capillary blood 25OHD compared to venous blood was 2.0 (95% CI: -7.5, 11.5) nmol/l.

CONCLUSION

Our study demonstrates excellent agreement with no evidence of a clinically important bias between venous and capillary serum 25OHD concentrations measured by LC/MS-MS over a wide range of values. Under those conditions, capillary blood is therefore adequate for the measurement of 25OHD.

Vitamin D and Diabetic Complications: True or False Prophet?

Vitamin D deficiency is now recognized as a condition of increasing prevalence worldwide. Vitamin D has an established role in calcium and bone metabolism; however, more recently associations with vitamin D deficiency and risk of developing diabetes, diabetes complications, and cardiovascular disease have all been acknowledged. The vitamin D receptor is ubiquitously expressed, and experimental, in vitro, and in vivo studies strongly suggest a role in regulating the transcription of multiple genes beyond calcium homeostasis. These include antiproliferative, immunomodulatory, angiogenic, inhibition of the renin-angiotensin-aldosterone system, and neurotrophic factor expression. Observational studies report a strong association between vitamin D deficiency and cardiovascular and metabolic disorders; however, there remains a paucity of large long-term randomized clinical trials showing a benefit with treatment. An increasing body of literature suggests a possible pathogenetic role of vitamin D in the long-term complications of diabetes and vitamin D deficiency may also exacerbate symptoms of painful diabetic peripheral neuropathy. It remains unknown if supplementation of vitamin D to normal or non-deficient levels alters pathogenetic processes related to diabetic microvascular complications. With the high prevalence of vitamin D deficiency in patients with diabetes and putative mechanisms linking vitamin D deficiency to diabetic complications, there is a compelling argument for undertaking large well-designed randomized controlled trials of vitamin D supplementation.

Vitamin D Deficiency Is Not Associated with Diabetic Retinopathy or Maculopathy

BACKGROUND

Experimental and clinical studies suggest a possible association between vitamin D deficiency and both diabetic retinopathy and maculopathy.

METHODS

We have performed a cross-sectional study in adults with types 1 and 2 diabetes mellitus. The relationship between the presence and severity of diabetic retinopathy and maculopathy with serum 25-hydroxyvitamin D concentration was evaluated using logistic regression analyses in the presence of demographic and clinical covariates.

RESULTS

657 adults with diabetes were stratified based on retinopathy grading: No Diabetic Retinopathy (39%), Background Diabetic Retinopathy (37%), Preproliferative Diabetic Retinopathy (21%), and Proliferative Diabetic Retinopathy (3%), respectively. There were no differences in serum 25-hydroxyvitamin D concentrations (25(OH)D) between the groups (15.3 ± 9.0 versus 16.4 ± 10.5 versus 15.9 ± 10.4 versus 15.7 ± 8.5 ng/mL, P = NS). Logistic regression analysis demonstrated no statistically significant relationship between the severity of retinopathy and serum 25(OH)D. Furthermore, there was no difference in serum 25(OH)D between those with (n = 94, 14%) and those without (n = 563, 86%) Diabetic Maculopathy (16.2 ± 10.0 versus 15.8 ± 9.8, P = NS) and no relationship was demonstrated by logistic regression analyses between the two variables.

CONCLUSIONS

This study has found no association between serum 25(OH)D and the presence and severity of diabetic retinopathy or maculopathy.

FGF-23/Vitamin D Axis in Type 1 Diabetes: The Potential Role of Mineral Metabolism in Arterial Stiffness

Objective

To investigate the usefulness of Fibroblast Growth Factor 23 (FGF-23) and vitamin D as possible biomarkers of pre-clinical atherosclerosis, assessed as arterial stiffness (AS), in a group of subjects with type 1 diabetes (T1DM) and no previous cardiovascular events.

Research Design and Methods

68 T1DM patients and 68 age- and sex-matched controls were evaluated for 1) age, sex, diabetes duration, physical activity, smoking, alcohol intake, BMI, blood pressure, fasting plasma glucose, HbA_1c, estimated glomerular filtration rate (eGFR) and lipid profile; 2) microvascular complications; 3) blood concentrations of FGF-23 and mineral metabolism parameters (calcium, phosphate, parathyroid hormone (PTH) and 25-hydroxy-vitamin D (25(OH)D)); 4) AS, assessed as aortic pulse wave velocity (aPWV); and 5) low-grade inflammation (hsCRP, IL-6, sTNFαR1, sTNFαR2) and endothelial dysfunction (ED) markers (ICAM-1, VCAM-1, E-Selectin).

Results

Patients with T1DM had higher aPWV compared with controls (p<0.001), but they did not present differences in 25(OH)D (70.3(50.4–86.2)nmol/L vs. 70.7(59.7–83.0)nmol/L; p = 0.462) and in FGF-23 plasma concentrations (70.1(38.4–151.9)RU/mL vs. 77.6(51.8–113.9)RU/mL; p = 0.329). In T1DM patients, higher concentrations of FGF-23 were positively associated with aPWV after adjusting for eGFR and classical cardiovascular risk factors (model 1: ß = 0.202, p = 0.026), other mineral metabolism parameters (model 2: ß = 0.214, p = 0.015), microvascular complications, low-grade inflammation and ED markers (model 3: ß = 0.170, p = 0.045). Lower 25(OH)D concentrations were also associated with higher aPWV after adjusting for all the above-mentioned factors (model 3: ß = -0.241, p = 0.015).

Conclusions

We conclude that both FGF-23 plasma concentrations (positively) and 25(OH)D serum concentrations (negatively) are associated with AS in patients with T1DM and no previous cardiovascular events.

Biomarkers in Diabetic Retinopathy

There is a global diabetes epidemic correlating with an increase in obesity. This coincidence may lead to a rise in the prevalence of type 2 diabetes. There is also an as yet unexplained increase in the incidence of type 1 diabetes, which is not related to adiposity. Whilst improved diabetes care has substantially improved diabetes outcomes, the disease remains a common cause of working age adult-onset blindness. Diabetic retinopathy is the most frequently occurring complication of diabetes; it is greatly feared by many diabetes patients. There are multiple risk factors and markers for the onset and progression of diabetic retinopathy, yet residual risk remains. Screening for diabetic retinopathy is recommended to facilitate early detection and treatment. Common biomarkers of diabetic retinopathy and its risk in clinical practice today relate to the visualization of the retinal vasculature and measures of glycemia, lipids, blood pressure, body weight, smoking, and pregnancy status. Greater knowledge of novel biomarkers and mediators of diabetic retinopathy, such as those related to inflammation and angiogenesis, has contributed to the development of additional therapeutics, in particular for late-stage retinopathy, including intra-ocular corticosteroids and intravitreal vascular endothelial growth factor inhibitors ('anti-VEGFs') agents. Unfortunately, in spite of a range of treatments (including laser photocoagulation, intraocular steroids, and anti-VEGF agents, and more recently oral fenofibrate, a PPAR-alpha agonist lipid-lowering drug), many patients with diabetic retinopathy do not respond well to current therapeutics. Therefore, more effective treatments for diabetic retinopathy are necessary. New analytical techniques, in particular those related to molecular markers, are accelerating progress in diabetic retinopathy research. Given the increasing incidence and prevalence of diabetes, and the limited capacity of healthcare systems to screen and treat diabetic retinopathy, there is need to reliably identify and triage people with diabetes. Biomarkers may facilitate a better understanding of diabetic retinopathy, and contribute to the development of novel treatments and new clinical strategies to prevent vision loss in people with diabetes. This article reviews key aspects related to biomarker research, and focuses on some specific biomarkers relevant to diabetic retinopathy.

Genome-wide analysis of DNA methylation in subjects with type 1 diabetes identifies epigenetic modifications associated with proliferative diabetic retinopathy

BACKGROUND

Epigenetic variation has been linked to several human diseases. Proliferative diabetic retinopathy (PDR) is a major cause of vision loss in subjects with diabetes. However, studies examining the association between PDR and the genome-wide DNA methylation pattern are lacking. Our aim was to identify epigenetic modifications that associate with and predict PDR in subjects with type 1 diabetes (T1D).

METHODS

DNA methylation was analyzed genome-wide in 485,577 sites in blood from cases with PDR (n = 28), controls (n = 30), and in a prospective cohort (n = 7). False discovery rate analysis was used to correct the data for multiple testing. Study participants with T1D diagnosed before 30 years of age and insulin treatment within 1 year from diagnosis were selected based on 1) subjects classified as having PDR (cases) and 2) subjects with T1D who had had diabetes for at least 10 years when blood DNA was sampled and classified as having no/mild diabetic retinopathy also after an 8.7-year follow-up (controls). DNA methylation was also analyzed in a prospective cohort including seven subjects with T1D who had no/mild diabetic retinopathy when blood samples were taken, but who developed PDR within 6.3 years (converters). The retinopathy level was classified by fundus photography.

RESULTS

We identified differential DNA methylation of 349 CpG sites representing 233 unique genes including TNF, CHI3L1 (also known as YKL-40), CHN2, GIPR, GLRA1, GPX1, AHRR, and BCOR in cases with PDR compared with controls. The majority of these sites (79 %) showed decreased DNA methylation in cases with PDR. The Natural Killer cell-mediated cytotoxicity pathway was found to be significantly (P = 0.006) enriched among differentially methylated genes in cases with PDR. We also identified differential DNA methylation of 28 CpG sites representing 17 genes (e.g. AHRR, GIPR, GLRA1, and BCOR) with P <0.05 in the prospective cohort, which is more than expected by chance (P = 0.0096).

CONCLUSIONS

Subjects with T1D and PDR exhibit altered DNA methylation patterns in blood. Some of these epigenetic changes may predict the development of PDR, suggesting that DNA methylation may be used as a prospective marker of PDR.

High prevalence of vitamin D deficiency and lack of association with subclinical atherosclerosis in asymptomatic patients with Type 1 Diabetes Mellitus from a Mediterranean area

AIMS

Several studies linked vitamin D deficiency with coronary artery disease (CAD). The aim of this study was to evaluate the relationship between the concentrations of 25-hydroxyvitamin D (25OHD) and the presence of early atherosclerosis in asymptomatic Type 1 Diabetes (T1D) patients with no previous history of ischemic heart disease.

METHODS

One hundred and forty-five patients with T1D (age 37.8 ± 8 years, 57 % male, all Caucasian, disease duration 20.6 ± 8.3 years, HbA1c 7.6 ± 1.4 % (60.2 ± 11.1 mmol/mol), body mass index (BMI) 25.2 ± 3.5 kg/m2, 52.4 % smokers, 23 % retinopathy, 10 % nephropathy) and 48 controls matched for age, sex, BMI and smoking habit were studied. 25OHD deficiency was defined for values ≤20 ng/mL. A sun exposure questionnaire, carotid ultrasonography to determine carotid intima-media thickness (CIMT) and the presence of atheroma plaques and cardiac computed tomography for evaluation of calcium artery calcification (CACS) were performed.

RESULTS

T1D subjects showed a high proportion of 25OHD deficiency (43.2 % vs. 21.7 %, p = 0.032). Of all, 82 % of T1D patients and 92 % of controls had a calcium score of 0. CIMT was greater in patients with T1D (0.55 ± 0.14 mm vs 0.48 ± 0.15, p = 0.01) compared with controls. T1D subjects showed no differences in the results of CACS or CIMT according to the vitamin D concentrations.

CONCLUSIONS

T1D patients have lower concentrations and twice more prevalence of 25OHD deficiency than controls. There was no association between 25OHD concentrations and subclinical CAD.