Effect of Vitamin D Supplementation on Glycemic Control in Patients With Type 2 Diabetes (SUNNY Trial): A Randomized Placebo-Controlled Trial

Variations of dietary intake by glycemic status and Hispanic/Latino heritage in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

OBJECTIVE

A healthy diet is important for diabetes prevention and control; however, few studies have assessed dietary intake among US Hispanics/Latinos, a diverse population with a significant burden of diabetes. To address this gap in the literature, we determined intake of energy, macro/micronutrients, and vitamin supplements among Hispanics/Latinos by glycemic status and heritage.

RESEARCH DESIGN AND METHODS

Cross-sectional study of adults aged 18-74 years from the Hispanic Community Health Study/Study of Latinos (2008-2011) with complete baseline data on glycemic status and two 24-hour dietary recalls (n=13 089). Age-adjusted and sex-adjusted and multivariable-adjusted measures of intake were determined by glycemic status and heritage.

RESULTS

Mean age-adjusted and sex-adjusted energy intake was significantly lower among Hispanics/Latinos with diagnosed diabetes compared with those with normal glycemic status (1665 vs 1873 kcal, P<0.001). Fiber intake was higher among those with diagnosed diabetes versus normal glycemic status (P<0.01). Among those with diagnosed diabetes, energy intake was highest among those with Cuban heritage compared with most other heritage groups (P<0.01 for all, except Mexicans), but there was no difference after additional adjustment. Fiber intake was significantly lower for those of Cuban heritage (vs Dominican, Central American, and Mexican), and sodium intake was significantly higher (vs all other heritage groups) (P<0.01 for all); findings were null after additional adjustment. There was no difference in supplemental intake of vitamin D, calcium, magnesium, or potassium by glycemic status.

CONCLUSIONS

As part of the care of Hispanics/Latinos with diabetes, attention should be made to fiber and sodium consumption.

Vitamin D and type 2 diabetes

Vitamin D deficiency is associated with a decreased insulin release, insulin resistance and type 2 diabetes in experimental and epidemiological studies. Animal studies show that 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) stimulates the pancreatic β-cell to secrete insulin. The relationship between vitamin D deficiency and insulin resistance could develop through inflammation, as vitamin D deficiency is associated with increased inflammatory markers. In addition, genetic polymorphisms of vitamin D -related genes may predispose to impaired glycemic control and type 2 diabetes. Epidemiologic studies showed an association between low serum 25-hydroxyvitamin D₃ (25(OH)D₃) concentration and an increased risk for the metabolic syndrome and type 2 diabetes. This may be partly explained by an increased fat mass. A possible causal relationship between vitamin D deficiency and type 2 diabetes should be proven by randomized clinical trials showing that either type 2 diabetes can be prevented or insulin release and insulin sensitivity can be improved by vitamin D supplements. The results of randomized clinical trials on the effect of vitamin D versus placebo, sometimes combined with calcium, in patients with impaired glucose tolerance ("prediabetes") or type 2 diabetes are inconsistent. Some studies showed a slight decrease of fasting plasma glucose or improvement of insulin resistance, but often only in posthoc analyses. These effects are mainly visible in patients with vitamin D deficiency and impaired glucose tolerance at baseline. Meta-analyses of randomized clinical trials in general did not show significant effects of vitamin D supplementation on glycemic control. Currently, several large scale randomized clinical trials with vitamin D supplementation in doses of 1600-4000IU/d are ongoing with glycemic control or incidence of diabetes mellitus as outcome. Vitamin D deficiency needs to be prevented or cured, but until the results of these trials are published, high-dose vitamin D supplementation cannot be recommended for prevention or amelioration of type 2 diabetes.

The Effect of Improved Serum 25-Hydroxyvitamin D Status on Glycemic Control in Diabetic Patients: A Meta-Analysis

BACKGROUND

Type 2 diabetes is a global health concern, with an increased prevalence and high cost of treatment.

OBJECTIVE

The aim of this systematic review and meta-analysis was to determine the effect of vitamin D supplementation and improved vitamin D status on glycemia and insulin resistance in type 2 diabetic patients.

DATA SOURCE

We searched PUBMED/Medline, Cumulative Index to Nursing and Allied Health, and Cochrane Library (until January 2017).

STUDY SELECTION

Prospective clinical trials were selected evaluating the impact of vitamin D supplementation on glycosylated hemoglobin (HbA1c), serum fasting plasma glucose (FPG), and homeostatic model assessment of insulin resistance (HOMA-IR) in diabetic patients.

DATA EXTRACTION AND SYNTHESIS

We used a random-effects model to synthesize quantitative data, followed by a leave-one-out method for sensitivity analysis. The systematic review registration was CRD42017059555. From a total of 844 entries identified via literature search, 24 controlled trials (1528 individuals diagnosed with type 2 diabetes) were included. The meta-analysis indicated a significant reduction in HbA1c [mean difference: -0.30%; 95% confidence interval (CI): -0.45 to -0.15, P < 0.001], FPG [mean difference: -4.9 mg/dL (-0.27 mmol/L); 95% CI: -8.1 to -1.6 (-0.45 to -0.09 mmol/L), P = 0.003], and HOMA-IR (mean difference: -0.66; 95% CI: -1.06 to -0.26, P = 0.001) following vitamin D supplementation and significant increase in serum 25-hydroxyvitamin D levels [overall increase of 17 ± 2.4 ng/mL (42 ± 6 nmol/L)].

CONCLUSIONS

Vitamin D supplementation, a minimum dose of 100 µg/d (4000 IU/d), may significantly reduce serum FPG, HbA1c, and HOMA-IR index, and helps to control glycemic response and improve insulin sensitivity in type 2 diabetic patients.

Vitamin D supplementation and glycemic control in type 2 diabetes patients: A systematic review and meta-analysis

INTRODUCTION

Low vitamin D status has been found to be associated with impaired glycemic control in patients who suffer from type 2 diabetes; however, whether vitamin D supplementation is associated with improved glycemic status remains controversial. The aim of this study was to summarize evidence from randomized controlled trials (RCTs) to assess the efficacy of vitamin D supplementation in reducing glycosylated haemoglobinA1c (HbA1c) and fasting blood glucose (FBG) levels.

MATERIALS/METHODS

We searched PubMed, Web of Science and the Cochrane Library for reports published up to March 2017. We selected parallel RCTs investigating the effect of vitamin D or vitamin D analogues on HbA1c or FBG levels in type 2 diabetes patients. Cohen's d was calculated to represent the standardized mean difference (SMD) for each study, and the SMDs with 95%confidence intervals (CIs) were pooled using a random effects model.

RESULTS

Twenty-four studies were included that evaluated HbA1c levels and 18 studies were included that evaluated FBG levels. Meta-analyses showed that vitamin D supplementation was associated with reduced HbA1c levels (standardized mean difference (SMD) -0.25 [-0.45 to -0.05]) but had no influence on FBG levels (SMD -0.14 [-0.31 to 0.03]). However, the subgroup analyses suggested that vitamin D supplementation was associated with reduced HbA1c levels (SMD -0.39 [-0.67 to -0.10]) and FBG (SMD -0.27 [-0.46 to -0.07]) among patients with 25-hydroxyvitamin D (25(OH) D) deficiency at baseline. Significantly reduced HbA1c levels were also observed in association with vitamin D supplementation in the subgroup including type 2 diabetes patients with a body mass index (BMI) <30kg m^-2 (SMD -0.30 [-0.54 to -0.07]).

CONCLUSIONS

Vitamin D supplementation could be effective at improving glycemic control in vitamin D deficient or non-obese type 2 diabetes patients.

Trends in dietary intake among adults with type 2 diabetes: NHANES 1988-2012

BACKGROUND

Dietary recommendations for adults with diabetes are to follow a healthy diet in appropriate portion sizes. We determined recent trends in energy and nutrient intakes among a nationally representative sample of US adults with and without type 2 diabetes.

METHODS

Participants were adults aged ≥20 years from the cross-sectional National Health and Nutrition Examination Surveys, 1988-2012 (N = 49 770). Diabetes was determined by self-report of a physician's diagnosis (n = 4885). Intake of energy and nutrients were determined from a 24-h recall by participants of all food consumed. Linear regression was used to test for trends in mean intake over time for all participants and by demographic characteristics.

RESULTS

Among adults with diabetes, overall total energy intake increased between 1988-1994 and 2011-2012 (1689 kcal versus 1895 kcal; Ptrend < 0.001) with evidence of a plateau between 2003-2006 and 2011-2012. In 2007-2012, energy intake was greater for younger than older adults, for men than women, and for non-Hispanic whites versus non-Hispanic blacks. There was no change in the percentage of calories from carbohydrate, total fat or protein. Percentage of calories from saturated fat was similar across study periods but remained above recommendations (11.2% in 2011-2012). Fibre intake significantly decreased and remained below recommendations (Ptrend = 0.002). Sodium, cholesterol and calcium intakes increased. There was no change in energy intake among adults without diabetes and dietary trends were similar to those with diabetes.

CONCLUSIONS

Future data are needed to confirm a plateau in energy intake among adults with diabetes, although the opportunity exists to increase fibre and reduce saturated fat.

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.

Effect of Vitamin D supplementation on reduction in levels of HbA1 in patients recently diagnosed with type 2 Diabetes Mellitus having asymptomatic Vitamin D deficiency

OBJECTIVE

To study the effect of Vitamin D supplementation on reduction in level of HbA1 in patients recently diagnosed with diabetes mellitus Type II having asymptomatic Vitamin D deficiency.

METHODS

This randomized control trial was conducted at East Medical Ward Mayo Hospital Lahore for 6 months from January 01 2016 to June 30, 2016. 114 Patients were included through non probability purposive sampling technique. Informed consent and demographic information was collected. Patients were divided in two groups by randomization through tossing a coin. Group-A patients received Metformin tablet alone at 500 mg after dinner and Group-B patients were treated with same dosage of Metformin along with oral vitamin D at 200,000 IU monthly for three months. Blood sample was obtained at baseline, 3 months and 6 months of initiation of therapy. All samples were sent to the laboratory for complete blood count, blood sugar fasting, serum calcium, serum phosphorous, serum alkaline phosphatase, HbA1c and serum 25 Hyroxy Vitamin D (S-25(OH) D) levels and iPTH. Data entry and analysis was done by using SPSS 20.

RESULTS

The mean age of patients in metformin group was 42.37±4.59 years while mean age of patients in combination group was 43.33±4.86years. Males were 45.6% and females were 54.4% in metformin group while in combination group, 36.8% were males' and 63.2% were females'. At baseline, in metformin group, mean Vitamin D level was 17.09±1.73mg/dl and in combination group, mean Vitamin D level was 16.49±1.56mg/dl. The difference was insignificant (p>0.05). On 2nd visit, combination group mean Vitamin D was 29.04±3.96mg/dl. At baseline, 1st and 2nd visit, in metformin group, mean HbA1c was 7.59±0.47%, 7.46±0.25% and 7.30±0.29%. At baseline, 1st and 2nd visit, in combination group, mean HbA1c was 7.71±0.19%, 7.57±0.21% and 7.43±0.26%. The difference was insignificant (p>0.05) at baseline while significant on later follow-ups (P<0.05).

CONCLUSION

Vitamin D supplementation improved the glycemic control but substantial reduction in HbA1c was statistically insignificant in both groups.

The effect of vitamin D supplementation on glucose metabolism in type 2 diabetes mellitus: A systematic review and meta-analysis of intervention studies

AIMS

We aimed to assess whether vitamin D supplementation improves glucose metabolism in adults with type 2 diabetes.

METHODS

PubMed and Cochrane database were searched up to July 1st 2016 for randomized controlled trials that assessed the relationship between vitamin D supplementation and glucose metabolism (change in hemoglobin A1C (HbA1C) and fasting blood glucose (FBG)) among adults with type 2 diabetes.

RESULTS

Twenty nine trials (3324 participants) were included in the systematic review. Among 22 studies included in the meta-analysis, 19 reported HbA1C, 16 reported FBG outcomes and 15 were deemed poor quality. There was a modest reduction in HbA1C (-0.32% [-0.53 to -0.10], I2=91.9%) compared to placebo after vitamin D supplementation but no effect on FBG (-2.33mg/dl [-6.62 to 1.95], I2=59.2%). In studies achieving repletion of vitamin D deficiency (n=7), there were greater mean reductions in HbA1C (-0.45%, [-1.09 to 0.20]) and FBG (-7.64mg/dl [-16.25 to 0.97]) although not significant.

CONCLUSIONS

We found a modest reduction of HbA1C after vitamin D treatment in adults with type 2 diabetes albeit with substantial heterogeneity between studies and no difference in FBG. Larger studies are needed to further evaluate the glycemic effects of vitamin D treatment especially in patients with vitamin D deficiency.

Patterns, control and complications of diabetes from a hospital based registry established in a low income country

BACKGROUND

Diabetes registry enables practitioners to measure the characteristics and patterns of diabetes across their patient population. They also provide insight into practice patterns which can be very effective in improving care and preventing complications. The aim of this study was to assess the patterns, control levels and complications at the baseline of the patients attending clinic at the large tertiary care hospital in Karachi, Pakistan with the help of the registry. This can be used as a reference to monitor the control and also for a comparison between peer groups.

METHODS

This was a cross sectional study with the data obtained from diabetes registry collected with the help of pre-designed questionnaire. HbA1c was used as a central diabetes measure and other related factors and complications were assessed with it.

RESULTS

Only 16.6% of the participants had optimal HbA1c ≤ 7.0%. 52.9% of the patients were classified as having poor control defined by HbA1c of >8%. Three fourth of the study population were obese according to Asian specific BMI cutoffs and majority had type 2 diabetes with duration of diabetes ranging from less than one to about 35 years, mean(SD) duration being 7.6 years (7.1). Overall only 4% of the patients were on combine target of HbA1c, LDL and BP. Results of multivariable logistic regression showed that the odds of having optimal glycemic control increased by 3% with every one year increase in age. In addition, having longer duration of diabetes was associated with 56% lower odds of having good glycemic control. Moreover, having higher triglyceride levels was associated with 1% lower odds of having good glycemic control.

CONCLUSION

This highlights the large burden of sub optimally controlled people with diabetes in Pakistani population, a low income country with huge diabetes prevalence and ineffective primary health care system creating enormous health and economic burden.

Vitamin D and diabetes mellitus: Causal or casual association?

The incidence of both type 2 and type 1 diabetes mellitus has been increasing worldwide. Vitamin D deficiency, or the awareness of its prevalence, has also been increasing. Vitamin D may have a role in the pathogenic mechanisms predisposing to type 2 diabetes by modulating insulin resistance and/or pancreatic β-cell function. Vitamin D status or elements involved in its activation or transport may also be involved in the development of type 1 diabetes mellitus through immunomodulatory role . Based on these observations a potential association between vitamin D and diabetes has been hypothesized. In this review we discuss up to date evidence linking vitamin D with the development of diabetes. Moreover, the role of vitamin D supplementation in the prevention of both types of diabetes is analysed together with its role in improving glycemic control in diabetic patients. We also address the potential role of vitamin D deficiency in the development of macro- and microvascular complications in diabetes. Finally, we provide recommendation for Vitamin D therapy in diabetes in view of current evidence and highlight areas for potential future research in this area.

Vitamin D and Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) has become a significant global health care problem and its reported incidence is increasing at an alarming rate. Despite the improvement in therapy and development of new drugs, treatment still remains insufficient especially due to the associated side effects of most available drugs. Efforts are continuing toward disease prevention and search for safer drugs. Conflicting evidence is associating low levels of vitamin D in the body to T2DM and as such studies have been conducted to test the effect of vitamin D levels on incidence of diabetes, diabetic control as well as diabetic complications.Despite the conflicting evidence, vitamin D replacement seems to have some beneficial effect on the many aspects of diabetes: incidence, control and complications. Further long term and more convincing controlled trials are required in order to draw firmer conclusions on this beneficial role of vitamin D treatment on T2DM.

Vitamin D Supplementation Improves Mood in Women with Type 2 Diabetes

OBJECTIVE

The aim of this study was to determine the effect of vitamin D supplementation on improving mood (depression and anxiety) and health status (mental and physical) in women with type 2 diabetes mellitus (T2DM).

METHODS

Fifty women with T2DM and significant depressive symptomology were enrolled into the "Sunshine Study," where weekly vitamin D supplementation (ergocalciferol, 50,000 IU) was given to all participants for six months. The main outcomes included (1) depression (Center for Epidemiologic Studies Depression, CES-D, and Patient Health Questionnaire, PHQ-9), (2) anxiety (State-Trait Anxiety), and (3) health status (Short Form, SF-12).

RESULTS

Forty-six women (92%) completed all visits. There was a significant decrease in depression (CES-D and PHQ-9, p < 0.001) and anxiety (state and trait, p < 0.001). An improvement in mental health status (SF-12, p < 0.001) was also found. After controlling for covariates (race, season of enrollment, baseline vitamin D, baseline depression (PHQ-9), and body mass index), the decline in depression remained significant (CES-D, p < 0.001). There was a trend for a better response to supplementation for women who were not taking medications for mood (antidepressants or anxiolytics) (p = 0.07).

CONCLUSIONS

Randomized trials to confirm that vitamin D supplementation can improve mood and health status in T2DM women are needed.

MANAGEMENT OF ENDOCRINE DISEASE: The effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

Epidemiologic studies suggest that vitamin D status plays a role in glycaemic control in patients with type 2 diabetes. However, intervention studies yielded inconsistent results. The aim of this study is to systematically review the effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes.

METHODS

Systematic review and meta-analysis. We searched Medline, Embase and the Cochrane Library for RCTs examining the effect of vitamin D supplementation on glycaemic control in patients with type 2 diabetes. A random-effects model meta-analysis was performed to obtain a summarized outcome of vitamin D supplementation on HbA_1c, fasting glucose and homeostasis model assessment - insulin resistance (HOMA-IR).

RESULTS

Twenty-three RCTs were included in this systematic review representing a total of 1797 patients with type 2 diabetes. Mean (± s.d.) change in serum 25-hydroxyvitamin D varied from 1.8 ± 10.2 nmol/L to 80.1 ± 54.0 nmol/L. Nineteen studies included HbA_1c as outcome variable. Combining these studies no significant effect in change of HbA_1c was seen after vitamin D intervention compared with placebo. A significant effect of vitamin D supplementation was seen on fasting glucose in a subgroup of studies (n = 4) with a mean baseline HbA_1c ≥ 8% (64 mmol/mol) (standardized difference in means: 0.36; 95% CI: 0.12-0.61, P = 0.003).

CONCLUSIONS

Current evidence of RCTs does not support short-term vitamin D supplementation in a heterogeneous population with type 2 diabetes. However, in patients with poorly controlled diabetes, a favourable effect of vitamin D is seen on fasting glucose.

Vitamin D-Cellular Ca2+ link to obesity and diabetes

The vitamin D hormone 1,25-Dihydroxyvitamin D₃ (1,25(OH)₂D₃)-induced cellular Ca²⁺ signals regulate apoptosis in adipocytes and insulin secretion from pancreatic β-cells, and low vitamin D status is considered a risk factor for obesity and type 2 diabetes. The anti-obesity effects of 1,25(OH)₂D₃ in mature adipocytes are determined by its activity to generate, via multiple Ca²⁺ signaling pathways, a sustained increase in intracellular Ca²⁺ followed by activation of the Ca²⁺-dependent initiators and effectors of apoptosis. In pancreatic β-cells, 1,25(OH)₂D₃ induces synchronous Ca²⁺ oscillations, which pattern pulsatile insulin secretion from these cells. An increased intake of vitamin D₃ in a high fat diet-induced obesity mouse model is associated with a decreased weight of white adipose tissue due to induction of apoptosis and the improved blood markers related to adiposity, diabetes, and vitamin D status (plasma concentrations of glucose, insulin, adiponectin, 25-hydroxyvitamin D, and 1,25(OH)₂D₃). High vitamin D₃ intake is also effective in increasing the mineral content of growing bone in obese mice via regulatory effects mediated by 1,25(OH)₂D₃-parathyroid hormone axis. The 1,25(OH)₂D₃-dependent cellular Ca²⁺ signaling can be important for maintaining the normal levels of apoptosis in adipose tissue and insulin secretion from pancreatic β-cells. An increased intake of vitamin D may contribute to the prevention of obesity, type 2 diabetes, and bone disorders associated with these diseases.

Plasma 25-Hydroxyvitamin D Is Related to Protein Signaling Involved in Glucose Homeostasis in a Tissue-Specific Manner

Vitamin D has been suggested to play a role in glucose metabolism. However, previous findings are contradictory and mechanistic pathways remain unclear. We examined the relationship between plasma 25-hydroxyvitamin D (25(OH)D), insulin sensitivity, and insulin signaling in skeletal muscle and adipose tissue. Seventeen healthy adults (Body mass index: 26 ± 4; Age: 30 ± 12 years) underwent a hyperinsulinemic-euglycemic clamp, and resting skeletal muscle and adipose tissue biopsies. In this cohort, the plasma 25(OH)D concentration was not associated with insulin sensitivity (r = 0.19, p = 0.56). However, higher plasma 25(OH)D concentrations correlated with lower phosphorylation of glycogen synthase kinase-3 (GSK-3) α^Ser21 and β^Ser9 in skeletal muscle (r = −0.66, p = 0.015 and r = −0.53, p = 0.06, respectively) and higher GSK-3 α^Ser21 and β^Ser9 phosphorylation in adipose tissue (r = 0.82, p < 0.01 and r = 0.62, p = 0.042, respectively). Furthermore, higher plasma 25(OH)D concentrations were associated with greater phosphorylation of both protein kinase-B (Akt^Ser473) (r = 0.78, p < 0.001) and insulin receptor substrate-1 (IRS-1^Ser312) (r = 0.71, p = 0.01) in adipose tissue. No associations were found between plasma 25(OH)D concentration and IRS-1^Tyr612 phosphorylation in skeletal muscle and adipose tissue. The divergent findings between muscle and adipose tissue with regard to the association between 25(OH)D and insulin signaling proteins may suggest a tissue-specific interaction with varying effects on glucose homeostasis. Further research is required to elucidate the physiological relevance of 25(OH)D in each tissue.

Ergocalciferol treatment does Not improve erythropoietin utilization and hospitalization rate in hemodialysis patients

BACKGROUND

Vitamin D (25-hydroxyvitamin D; 25[OH]D) deficiency (VDD) is highly prevalent in chronic kidney disease. The aim of this study was to evaluate the effect of oral ergocalciferol supplementation on requirement of erythropoietin (EPO) and active vitamin D analogues, and hospitalization rate in maintenance hemodialysis (HD) patients.

METHODS

This retrospective cohort study included 186 patients who were on HD for 3 months and had 25(OH)D levels < 30 ng/ml. Over 1-year period, 107 patients were supplemented with protocol-based ergocalciferol (D2 group) and 79 were not (control). Parameters of erythropoiesis and bone-mineral metabolism, and monthly doses of EPO and paricalcitol were assessed at 6- and 12- months of ergocalciferol supplementation. Total hospitalizations were recorded for the same year.

RESULTS

Baseline characteristics were similar across two arms except higher serum ferritin, transferrin saturation and prevalence of stroke in D2 and higher coronary artery disease in control group with overall mean ± SD 25(OH)D level of 16.8 ± 7 ng/ml. At 12 months, 25(OH)D levels increased significantly in D2 group compared to control (30.5 ± 11.7 vs. 14.2 ± 9.3 ng/ml; p < 0.001). The EPO dose remained same with no difference in hemoglobin values between the two groups during the intervention period. On multivariate regression which included above variables there was no effect of ergocalciferol treatment on EPO dose (p = ns). Hospitalization rate was similar in two arms; however, ergocalciferol treatment inversely associated with paricalcitol dose (β ± SE = -10.4 ± 2.8; p < 0.001).

CONCLUSIONS

One-year of ergocalciferol supplementation was not associated with reduction in EPO requirement or hospitalization rate in HD patients with VDD. Further studies are warranted to determine definitive role of nutritional vitamin D in these patients.

The effect of a single dose of vitamin D on glycemic status and C-reactive protein levels in type 2 diabetic patients with ischemic heart disease: a randomized clinical trial

AIMS

To assess whether a single parental dose of 25-hydroxy vitamin D [25(OH)Vit D] could improve glucose control and inflammation in type 2 diabetic patients (T2D) with ischemic heart disease (IHD).

METHODS

A randomized, placebo-controlled, double-blind trial was performed on 95 patients (47-placebo and 48-vitamin D groups). Participants were randomized using a randomization table to a single dose of either vitamin D (300,000 IU, IM) or a matching placebo. Fasting blood sugar (FBS), glycosylated hemoglobin (HbA1c), 25(OH)Vit D and high-sensitivity C-reactive protein (hs-CRP) were measured at baseline and at 8 weeks.

RESULTS

No significant differences in baseline values were noted between groups, except in HbA1c, which was lower in the placebo group. In the supplemented group, the level of serum 25(OH)Vit D increased (29.6 ± 20.8 vs. 44.5 ± 19.2 ng/mL) and those of FBS and HbA1c decreased significantly [186.5 ± 64.1 vs. 165.1 ± 58.5 mg/dL and 8.2 ± 2.0 % (66.3 ± 21.8 mmol/mol) vs. 7.7 ± 1.8 % (61.7 ± 20.0 mmol/mol), respectively] (all p < 0.05), and no changes, however, were observed in the placebo group. We also compared change of marginal means of outcome variables (HbA1c, FBS, 25(OH)Vit D and hs-CRP) from baseline between the vitamin D versus placebo group, using ANCOVA, adjusted for the baseline of each variable itself, season at study entry, age and body mass index. During trial, only HbA1c level decreased significantly [0.48 % (standard error: 0.17), p = 0.04]. No any adverse effect was seen.

CONCLUSIONS

A single parenteral dose of vitamin D in T2D patients with IHD improved glycemic control, but not inflammatory status.

CLINICAL TRIAL REGISTRY

Australian New Zealand Clinical Trial Registry.

CLINICAL TRIAL NUMBER

ACTRN12614000529640.

Vitamin D3 supplementation, bone health and quality of life in adults with diabetes and chronic kidney disease: Results of an open label randomized clinical trial

BACKGROUND

Adults with diabetes (DM) and chronic kidney disease (CKD) are at risk for vitamin D (vitD) insufficiency, suboptimal bone health and reduced quality of life (QoL) due to limited sunlight exposure, poor vitD intake and CKD.

AIMS

This open-labeled, randomized clinical trial, compared the impact of daily (2000 IU/D) verses monthly (40,000 IU/month) vitD₃ supplementation over six months on markers of vitD status, bone health and QoL in adults with DM and CKD (stages: 1-4).

METHODS

Participants (18-80 years) were randomized to daily (n = 60) or monthly (n = 60) vitD₃ for six months. Primary outcomes included: vitD status (25-hydroxyvitD [25(OH)D], 1, 25-dihydroxyvitD [1,25(OH)₂D], bone health (bone mineral density [BMD] and serum concentrations of bone-specific alkaline phosphatase [BSAP], osteocalcin [OC], N-telopeptide-type 1-collagen [NTx]) and Fibroblast Growth Factor-23 (FGF-23). Secondary outcomes included QoL (Short Form-36 questionnaire).

RESULTS

Adherence by dose allocation over six months was 95.0 ± 5.7% (daily) and 94.1 ± 4.1% (monthly), respectively (p = 0.44); resulting in an overall median [95% CI] increase in serum 25(OH)D of 19 (12-26) nmol/L (p < 0.001). Serum 25(OH)D increased at three (p < 0.001) and six months (p < 0.001) in the daily and monthly groups, respectively. No significant differences over six months between groups were observed in serum concentrations of 1,25(OH)₂D, FGF-23, OC and NTx, BMD and QoL measures (p > 0.05). Serum 25(OH)D ≥ 75 nmol/L was associated with significant reductions in BSAP (p = 0.01) and improved physical functioning vs those with concentrations < 75 nmol/L (62.5 ± 26.8 vs 52.7 ± 26.3; p = 0.03) in the monthly and daily groups, respectively.

CONCLUSIONS

Daily (2000 IU/D) and monthly (40,000 IU/month) vitD₃ supplementation for six months in adults with DM and CKD was safe, and resulted in equivalent adherence and improvements in overall vitD status, but only modest changes in markers of bone health and QoL.

The Potential Protective Action of Vitamin D in Hepatic Insulin Resistance and Pancreatic Islet Dysfunction in Type 2 Diabetes Mellitus

Vitamin D deficiency (i.e., hypovitaminosis D) is associated with increased insulin resistance, impaired insulin secretion, and poorly controlled glucose homeostasis, and thus is correlated with the risk of metabolic diseases, including type 2 diabetes mellitus (T2DM). The liver plays key roles in glucose and lipid metabolism, and its dysregulation leads to abnormalities in hepatic glucose output and triglyceride accumulation. Meanwhile, the pancreatic islets are constituted in large part by insulin-secreting β cells. Consequently, islet dysfunction, such as occurs in T2DM, produces hyperglycemia. In this review, we provide a critical appraisal of the modulatory actions of vitamin D in hepatic insulin sensitivity and islet insulin secretion, and we discuss the potential roles of a local vitamin D signaling in regulating hepatic and pancreatic islet functions. This information provides a scientific basis for establishing the benefits of the maintenance, or dietary manipulation, of adequate vitamin D status in the prevention and management of obesity-induced T2DM and non-alcoholic fatty liver disease.

Vitamin D and Evening Primrose Oil Administration Improve Glycemia and Lipid Profiles in Women with Gestational Diabetes

Limited data are available assessing the effects of vitamin D and evening primrose oil (EPO) administration on markers of insulin resistance and lipid concentrations in gestational diabetes mellitus (GDM). This study was designed to evaluate the effects of vitamin D and EPO administration on insulin resistance and lipid concentrations among women with GDM. In this prospective randomized, double-blind, placebo-controlled clinical trial, 60 participants with GDM were divided into 2 groups of either 1000 IU vitamin D3 and 1000 mg EPO or placebo for 6 weeks. At the beginning and end of the study, fasting blood samples were obtained from the participants to measure related variables. After 6 weeks of intervention, changes in fasting plasma glucose (-3.6 ± 7.5 vs. +1.5 ± 11.4 mg/dL, P = 0.04), serum insulin concentrations (-2.0 ± 5.3 vs. +4.6 ± 10.7 µIU/mL, P = 0.004), homeostasis model of assessment (HOMA) insulin resistance (-0.5 ± 1.1 vs. +1.1 ± 2.5, P = 0.003), HOMA-B cell function (-7.7 ± 23.3 vs. +17.4 ± 42.9, P = 0.007) and the quantitative insulin sensitivity check index (+0.01 ± 0.02 vs. -0.01 ± 0.02, P = 0.007) in the vitamin D plus EPO group were significantly different from the placebo group. In addition, compared with the placebo, vitamin D and EPO supplementation resulted in significant reductions in serum TAG (-20.0 ± 54.3 vs. +34.3 ± 38.2 mg/dL, P < 0.001), VLDL (-4.0 ± 10.9 vs. +6.9 ± 7.6 mg/dL, P < 0.001), TC (-22.1 ± 32.6 vs. +5.3 ± 20.1 mg/dL, P < 0.001), LDL concentrations (-18.0 ± 25.5 vs. +1.8 ± 15.7 mg/dL, P = 0.001) and TC/HDL (-0.3 ± 0.4 vs. +0.3 ± 0.5 mg/dL, P < 0.001). We did not observe any significant effect of vitamin D and EPO supplementation on serum HDL concentrations.

CLINICAL TRIAL REGISTRATION NUMBER

http://www.irct.ir : IRCT201509115623N52.

No Effect of High-Dose Vitamin D Treatment on β-Cell Function, Insulin Sensitivity, or Glucose Homeostasis in Subjects With Abnormal Glucose Tolerance: A Randomized Clinical Trial

OBJECTIVE

There has been conflicting evidence regarding the potential role of vitamin D in glucose homeostasis. This study was designed to investigate the effect of high-dose vitamin D3 treatment on β-cell function, insulin sensitivity, and glucose tolerance in subjects with prediabetes or diet-treated type 2 diabetes.

RESEARCH DESIGN AND METHODS

Subjects (n = 44) were randomized to 30,000 IU vitamin D3 once weekly or placebo for 8 weeks. Hyperglycemic clamp assessed first-phase (0-12 min) and second-phase (12-120 min) insulin response, insulin sensitivity, and disposition index (DI). An oral glucose tolerance test assessed glucose tolerance and glycosylated hemoglobin assessed glycemic control.

RESULTS

A total of 21 (vitamin D) and 22 (placebo) subjects completed the study, respectively. Season-adjusted 25-OH-vitamin D [25(OH)D] levels were doubled in the active treated group (43-82 nmol/L). No effect of vitamin D treatment, compared with placebo, was seen on first-phase or second-phase insulin secretion. There were no group differences in insulin sensitivity, DI, or any measures of glycemic control. No hypercalcemia or other adverse effects of vitamin D treatment were seen compared with placebo. Subgroup analyses of those with the lowest basal and greatest increase in 25(OH)D levels did not change these results.

CONCLUSIONS

This study gives no support for any substantial effect of high-dose vitamin D treatment for 8 weeks in prediabetes or diet-treated type 2 diabetes on β-cell function, insulin sensitivity, or glycemic control.

1,25-Dihydroxyvitamin D3 and type 2 diabetes: Ca2+-dependent molecular mechanisms and the role of vitamin D status

The hormone 1,25-dihydroxyvitamin D

Vitamin D status is associated with skin autofluorescence in patients with type 2 diabetes mellitus: a preliminary report

Background

Skin autofluorescence is a non-invasive measurement of advanced glycation end products (AGE), which are suggested to be one of the major agents in the pathogenesis and progression of diabetes related cardiovascular complications. Recently, low vitamin D status has been linked to the progression of type 2 diabetes mellitus (T2DM) and cardiovascular disease. The aim of this study is to investigate the association between vitamin D status and skin autofluorescence in patients with T2DM.

Methods

In this preliminary report skin autofluorescence was measured non-invasively with an AGE-reader in 245 patients with T2DM treated with lifestyle advice, metformin and/or sulphonylurea-derivatives. All patients were randomly assigned to receive either vitamin D 50,000 IU/month or placebo for 6 months.

Results

Skin autofluorescence was significantly higher in patients with a serum 25(OH)D <50 nmol/l compared to patients with a serum 25(OH)D >75 nmol/l (2.81 versus 2.41; p < 0.001). Mean serum 25(OH)D was 60.3 ± 23.4 nmol/l and was independently associated with skin autofluorescence (β −0.006; p < 0.001). Mean vitamin D increased from 60.8 to 103.6 nmol/l in the intervention group, however no effect was seen on accumulation of skin AGEs after 6 months compared to placebo.

Conclusions

Vitamin D status is independently associated with skin auto fluorescence in patients with well-controlled T2DM. No effect was seen on the amount of skin AGEs after a short period of 6 months vitamin D supplementation. Further research with longer follow-up and measurement of circulating advanced glycation end products is needed to elucidate the causality of the association.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0250-z) contains supplementary material, which is available to authorized users.