Nephropathy in type 1 diabetes: a manifestation of insulin resistance and multiple genetic susceptibilities? Further evidence from the Pittsburgh Epidemiology of Diabetes Complication Study

Insulin sensitivity estimates and their longitudinal association with coronary artery disease in type 1 diabetes. Does it matter?

BACKGROUND

Insulin resistance and chronic kidney disease are both associated with increased coronary artery disease risk. Many formulae estimating glucose disposal rate in type 1 diabetes infer insulin sensitivity from clinical data. We compare associations and performance relative to traditional risk factors and kidney disease severity between three formulae estimating the glucose disposal rate and coronary artery disease in people with type 1 diabetes.

METHODS

The baseline glucose disposal rate was estimated by three (Williams, Duca, and Januszewski) formulae in FinnDiane Study participants and related to subsequent incidence of coronary artery disease, by baseline kidney status.

RESULTS

In 3517 adults with type 1 diabetes, during median (IQR) 19.3 (14.6, 21.4) years, 539 (15.3%) experienced a coronary artery disease event, with higher rates with worsening baseline kidney status. Correlations between the three formulae estimating the glucose disposal rate were weak, but the lowest quartile of each formula was associated with higher incidence of coronary artery disease. Importantly, only the glucose disposal rate estimation by Williams showed a linear association with coronary artery disease risk in all analyses. Of the three formulae, Williams was the strongest predictor of coronary artery disease. Only age and diabetes duration were stronger predictors. The strength of associations between estimated glucose disposal rate and CAD incidence varied by formula and kidney status.

CONCLUSIONS

In type 1 diabetes, estimated glucose disposal rates are associated with subsequent coronary artery disease, modulated by kidney disease severity. Future research is merited regarding the clinical usefulness of estimating the glucose disposal rate as a coronary artery disease risk factor and potential therapeutic target.

Insulin Resistance in Adolescents and Youth With Type 1 Diabetes: A Review of Problems and Solutions

Though insulin resistance (IR) was previously considered a feature of only type 2 Diabetes (T2DM), its development in type 1 Diabetes (T1DM) is not an uncommon occurrence, the causes of which are multifactorial (gender, pubertal status, diabetes duration, ethnicity, genetics, adiposity, glycemic control, chronic inflammation). Despite improvements in glucose, blood pressure and lipid profile, vascular complications (coronary artery disease and nephropathy) continue to remain common causes of morbidity and mortality in T1DM. Aggressive glycemic control reduces but does not eliminate the risk of IR. IR accelerates the development of micro and macrovascular complications, many of which can be potentially reversed if diagnosed and managed early. Lack of endogenous insulin production makes estimation of insulin sensitivity in T1DM difficult. As hyperinsulinemic-euglycemic clamp studies are cumbersome and invasive, the use of prediction equations for calculating estimated insulin sensitivity may prove to be useful. Along with intensive insulin therapy, dietary modifications and increasing physical activity, the role of Metformin in managing IR in T1DM is becoming increasingly popular. Metformin adjunct therapy in T1DM has been shown to improve insulin sensitivity, glycemic control, lipid profile, body composition, vascular smooth muscle function, thereby reducing the risk of vascular complications, as well as reversal of early vascular dysfunction. However, further studies to assess long-term efficacy and safety of Metformin use in adolescents and youth with T1DM are needed. This review aims at revisiting the pathophysiology of IR in T1DM and techniques of identifying those at risk so as to put into action various strategies for management of the same.

Estimated Glucose Disposal Rate Predicts Renal Progression in Type 2 Diabetes Mellitus: A Retrospective Cohort Study

Context

Insulin resistance is a feature of type 2 diabetes mellitus (T2DM). The estimated glucose disposal rate (eGDR), a validated marker for insulin resistance, is associated with complications of diabetes, but few studies have explored the relationship between eGDR and renal outcomes in T2DM.

Objective

This study investigated the value of eGDR in predicting renal progression in T2DM.

Methods

A total of 956 T2DM patients with a baseline estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m² and 5 years of follow-up were enrolled. Primary outcomes were rapid eGFR decline, eGFR <60 mL/min/1.73 m², and composite renal endpoint consisting of 50% eGFR decline, doubling of serum creatinine, or end-stage renal disease. A continuous scale with restricted cubic spline curves and a generalized linear model were applied to evaluate the associations between eGDR and primary outcomes.

Results

Rapid eGFR decline was experienced by 23.95% of patients, 21.97% with eGFR <60 mL/min/1.73 m², and 12.13% with the composite renal endpoint. The eGDR showed a relationship with follow-up eGFR and percentage change in eGFR (P < .001). An eGDR <6.34 mg/kg/min was an independent risk factor for rapid eGFR decline, eGFR < 60 mL/min/1.73 m², or the composite renal endpoint(P < .05). Compared with eGDR of 5.65∼6.91 mg/kg/min, eGDR levels >8.33 mg/kg/min decreased the risk of rapid eGFR decline by 75%, eGFR < 60 mL/min/1.73 m² by 60%, and the composite renal endpoint by 61%. Subgroup analysis was performed by sex, age, and diabetes duration, which showed that eGDR was associated with primary outcomes.

Conclusion

Lower eGDR is a predictive factor for renal deterioration in T2DM patients.

Estimated glucose disposal rate is associated with retinopathy and kidney disease in young people with type 1 diabetes: a nationwide observational study

AIMS

The aim of this study was to investigate the association between estimated glucose disposal rate (eGDR), a proxy for insulin resistance, and retinopathy or kidney disease, i.e. micro-, or macroalbuminuria, in young individuals with type 1 diabetes (T1D).

MATERIAL AND METHODS

Using data from the Swedish pediatric registry for diabetes (SweDiabKids) and the registry for adults (NDR), all individuals with T1D with a duration of diabetes of less than 10 years between 1998 and 2017 were included. We calculated the crude incidence rates with 95% confidence intervals (CIs) and used multivariable Cox regression to estimate crude and adjusted hazard ratios (HRs) for two cohorts: retinopathy cohort or kidney disease cohort, stratified by eGDR categories: < 4, 4 to 5.99, 6 to 7.99, and ≥ 8 mg/kg/min (reference).

RESULTS

A total of 22 146 (10 289 retinopathy cohort, and 11 857 kidney disease cohort with an overlapping of 9575) children and adults with T1D (median age 21 years, female 42% and diabetes duration of 6 and 7 years, respectively for the cohorts) were studied. During a median follow-up of 4.8 years (IQR 2.6-7.7) there were 5040 (24.7%), 1909 (48.1%), 504 (52.3%) and 179 (57.6%) events for retinopathy in individuals with an eGDR ≥ 8, 7.99 to 6, 5.99 to 4, and < 4 mg/kg/min, respectively. Corresponding numbers for kidney disease was 1321 (6.5%), 526 (13.3%), 255 (26.8%) and 145 (46.6%). After multiple adjustments for different covariates, individuals with an eGDR 7.99 to 6, 5.99 to 4 and < 4 mg/kg/min, had an increased risk of retinopathy compared to those with an eGDR ≥ 8 mg/kg/min (adjusted HRs, 95% CIs) 1.29 (1.20 to 1.40); 1.50 (1.31 to 1.71) and 1.74 (1.41 to 2.14). Corresponding numbers for kidney disease was (adjusted HRs, 95% CIs) 1.30 (1.11 to 1.52); 1.58 (1.25 to 1.99) and 1.33 (0.95 to 1.86), respectively.

CONCLUSIONS

eGDR, a proxy for insulin resistance, is associated with retinopathy and kidney disease in young adults with T1D. The risk of retinopathy increased with lower eGDR. The risk of kidney disease also increased with lower eGDR; however results show no association between the lowest eGDR and kidney disease. eGDR can be helpful to identify young T1D individuals at risk.

Association of parental cardiovascular risk factors with offspring type 1 diabetes mellitus insulin sensitivity

AIM

This study aimed to determine whether the insulin resistance (IR) and lipid profiles in Type 1 Diabetes (T1D) offspring are associated with IR and other cardiovascular risk factors in their parents.

METHODS

This study included 99 T1D patients (19.6 ± 4.0 yrs.), 85 mothers and 60 fathers. Parents' IR was assessed by HOMA-IR, and the insulin sensitivity in T1D patients was assessed by the estimated Glucose Disposal Rate (eGDR).

RESULTS

The eGDR in the T1D offspring was negatively related to age (p = 0.023), weight (p = 0.004), LDL (p = 0.026), and microalbuminuria (p = 0.019). Maternal Type 2 Diabetes (p < 0.001) and HOMA-IR (p = 0.029) were negatively related to eGDR in their T1D offspring. The maternal HOMA-IR and the proband's eGDR were positively (p = 0.012) and negatively (p = 0.042) associated with the birth weight of the T1D offspring, respectively. We didn't find an association with the fathers' profiles.

CONCLUSIONS

In a cohort of offspring with T1D the insulin sensitivity was related to the IR, lipid profile, and the presence of T2D only in their mothers. Precocious screening and treatment of these risk factors beyond glycemic control will benefit T1D with this background.

Relationship Between Estimated Glucose Disposal Rate and Type 2 Diabetic Retinopathy

PURPOSE

To investigate the association between diabetic retinopathy (DR), DR intensity, and estimated glucose disposal rate (eGDR) in individuals with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

This study comprised 1762 T2DM patients who were admitted between January and December, 2021. Overall, the DR was identified in 430 patients. Based on the eGDR, the participants were divided into four study groups. One-way analysis of variance was used to compare the groups. The correlations between eGDR and DR risk, eGDR, and DR severity were analyzed using regression analysis. Furthermore, these relationships were analyzed in different sex groups.

RESULTS

Patients with T2DM had a 19.75% (348/1762) DR detection rate, whereas those with DR had a 22.41% (78/348) proliferative DR detection rate. The DR group had substantially reduced levels of eGDR compared with the non-DR group. Multivariate logistic regression analysis demonstrated that reduced eGDR was an independent risk factor for DR, after adjusting for confounding variables. eGDR correlated significantly with proliferative DR in women but not in men.

CONCLUSION

In Chinese individuals with T2DM, lower eGDR was independently associated with a higher risk of DR.

Highlighting the Role of Obesity and Insulin Resistance in Type 1 Diabetes and Its Associated Cardiometabolic Complications

PURPOSE OF REVIEW

This narrative review appraises research data on the potentially harmful effect of obesity and insulin resistance (IR) co-existence with type 1 diabetes mellitus (T1DM)-related cardiovascular (CVD) complications and evaluates possible therapeutic options.

RECENT FINDINGS

Obesity and IR have increasingly been emerging in patients with T1DM. Genetic, epigenetic factors, and subcutaneous insulin administration are implicated in the pathogenesis of this coexistence. Accumulating evidence implies that the concomitant presence of obesity and IR is an independent predictor of worse CVD outcomes. The prevalence of obesity and IR has increased in patients with T1DM. This increase can be partly attributed to general population trends but, additionally, to iatrogenic weight gain caused by insulin treatment. This association might be the missing link explaining the excess CVD burden observed in patients with T1DM despite optimal glycemic control. Data on newer agents for type 2 diabetes mellitus (T2DM) treatment are unraveling novel ways to challenge this aggravating coexistence.

HDL cholesterol is a protective predictor in the development and progression of retinopathy in type 1 diabetes: A 15-year follow-up study

AIMS

To evaluate the 15-year incidence of development and progression of diabetic retinopathy (DR) in type 1 diabetic patients (T1DM) and determine the associated risk factors.

METHODS

123 T1DM were included in this prospective cohort study and followed for 15 years. Demographic, clinical, laboratory parameters, and retinal photographs were collected and analyzed. Risk factors for DR development and progression were identified using Cox regression analysis.

RESULTS

At baseline, 87 (71%) patients had no DR, and 36 (29%) had nonproliferative DR (NPDR). After 15 years, 54 patients (43.9%; 29.3/1000 person-years) developed NPDR or progressed to proliferative DR (PDR); 24 (27.6%) developed new NPDR, and 30 (83.3%) progressed to PDR. HbA₁c (HR = 1.48, p = 0.008) and urinary albumin excretion rate (AER) (HR = 1.58, p = 0.045) were associated with the risk of DR development and progression, and a protective association was found for HDL cholesterol (HR = 0.17, p = 0.021). The presence of DR at baseline (HR = 2.95, p = 0.023) was associated with the risk of its progression to PDR.

CONCLUSIONS

The 15-year incidence of DR development and progression in T1DM is still very high, which points to the need for close monitoring of T1DM, especially those with higher HbA₁c, higher AER, the initial presence of DR, and lower HDL cholesterol.

MicroRNAs and their delivery in diabetic fibrosis

The global prevalence of diabetes mellitus was estimated to be 463 million people in 2019 and is predicted to rise to 700 million by 2045. The associated financial and societal costs of this burgeoning epidemic demand an understanding of the pathology of this disease, and its complications, that will inform treatment to enable improved patient outcomes. Nearly two decades after the sequencing of the human genome, the significance of noncoding RNA expression is still being assessed. The family of functional noncoding RNAs known as microRNAs regulates the expression of most genes encoded by the human genome. Altered microRNA expression profiles have been observed both in diabetes and in diabetic complications. These transcripts therefore have significant potential and novelty as targets for therapy, therapeutic agents and biomarkers.

Insulin Resistance is Associated with Clinical Manifestations of Diabetic Kidney Disease (Glomerular Hyperfiltration, Albuminuria, and Kidney Function Decline)

Clinical features of diabetic kidney disease include glomerular hyperfiltration, albuminuria, and kidney function decline towards End-Stage Kidney Disease (ESKD). There are presently neither specific markers of kidney involvement in patients with diabetes nor strong predictors of rapid progression to ESKD. Serum-creatinine-based equations used to estimate glomerular filtration rate are notoriously unreliable in patients with diabetes. Early kidney function decline, reduced glomerular filtration rate, and proteinuria contribute to identifying diabetic patients at higher risk for rapid kidney function decline. Unlike proteinuria, the elevation of urinary albumin excretion in the range of microalbuminuria is frequently transient in patients with diabetes and does not always predict progression towards ESKD. Although the rate of progression of kidney function decline is usually accelerated in the presence of proteinuria, histological lesions of diabetes and ESKD may occur with normal urinary albumin excretion. No substantial reduction in the rate of ESKD associated with diabetes has been observed during the last decades despite intensified glycemic control and reno-protective strategies, indicating that existing therapies do not target underlying pathogenic mechanisms of kidney function decline. Very long-term effects of sodium-glucose transporters- 2 inhibitors and glucagon-like peptide-1 analogs remain to be defined. In patients with diabetes, glucagon secretion is typically elevated and induces insulin resistance. Insulin resistance is consistently and strongly associated with clinical manifestations of diabetic kidney disease, suggesting that reduced insulin sensitivity participates in the pathogenesis of the disease and may represent a therapeutic objective. Amelioration of insulin sensitivity in patients with diabetes is associated with cardioprotective and kidney-protective effects.

Estimated glucose disposal rate as a candidate biomarker for thrombotic biomarkers in T1D: a pooled analysis

PURPOSE

To determine the utility of estimated glucose disposal rate (eGDR) as a candidate biomarker for thrombotic biomarkers in patients with type 1 diabetes (T1D).

METHODS

We reanalysed baseline pretreatment data in a subset of patients with T1D from two previous RCTs, consisting of a panel of thrombotic markers, including fibrinogen, tissue factor (TF) activity, and plasminogen-activator inhibitor (PAI)-1, and TNFα, and clinical factors (age, T1D duration, HbA1c, insulin requirements, BMI, blood pressure, and eGDR). We employed univariate linear regression models to investigate associations between clinical parameters and eGDR with thrombotic biomarkers.

RESULTS

Thirty-two patients were included [mean ± SD age 31 ± 7 years, HbA1c of 58 ± 9 mmol/mol (7.5 ± 0.8%), eGDR 7.73 ± 2.61]. eGDR negatively associated with fibrinogen (P < 0.001), PAI-1 concentrations (P = 0.005), and TF activity (P = 0.020), but not TNFα levels (P = 0.881). We identified 2 clusters of patients displaying significantly different characteristics; 56% (n = 18) were categorised as 'higher-risk', eliciting significantly higher fibrinogen (+ 1514 ± 594 μg/mL; P < 0.001), TF activity (+ 59.23 ± 9.42 pmol/mL; P < 0.001), and PAI-1 (+ 8.48 ± 1.58 pmol/dL; P < 0.001), HbA1c concentrations (+ 14.20 ± 1.04 mmol/mol; P < 0.001), age (+ 7 ± 3 years; P < 0.001), duration of diabetes (15 ± 2 years; P < 0.001), BMI (+ 7.66 ± 2.61 kg/m²; P < 0.001), and lower mean eGDR (- 3.98 ± 1.07; P < 0.001).

CONCLUSIONS

Compared to BMI and insulin requirements, classical surrogates of insulin resistance, eGDR is a suitable and superior thrombotic risk indicator in T1D.

TRIAL REGISTRATION

ISRCTN4081115; registered 27 June 2017.

The Multiple Roles of Fibroblast Growth Factor in Diabetic Nephropathy

Diabetic nephropathy (DN) is a common microvascular complication in the late stages of diabetes. Currently, the etiology and pathogenesis of DN are not well understood. Even so, available evidence shows its development is associated with metabolism, oxidative stress, cytokine interaction, genetic factors, and renal microvascular disease. Diabetic nephropathy can lead to proteinuria, edema and hypertension, among other complications. In severe cases, it can cause life-threatening complications such as renal failure. Patients with type 1 diabetes, hypertension, high protein intake, and smokers have a higher risk of developing DN. Fibroblast growth factor (FGF) regulates several human processes essential for normal development. Even though FGF has been implicated in the pathological development of DN, the underlying mechanisms are not well understood. This review summarizes the role of FGF in the development of DN. Moreover, the association of FGF with metabolism, inflammation, oxidative stress and fibrosis in the context of DN is discussed. Findings of this review are expected to deepen our understanding of DN and generate ideas for developing effective prevention and treatments for the disease.

Association of estimated glucose disposal rate and chronic diabetic complications in patients with type 1 diabetes

Introduction

The role of insulin resistance in diabetic chronic complications among individuals with type 1 diabetes (T1D) has not been clearly defined. The aim of this study was to examine the performance of insulin resistance, evaluated using the estimated glucose disposal rate (eGDR) for the identification of metabolic syndrome (MS) and diabetic chronic complications.

Methods

Cross‐sectional study in a tertiary care centre. We included patients of 18 years and older, with at least 6 months of T1D duration. Anthropometric, clinical and biochemical data were collected.

Results

Seventy patients, 41 (58.6%) women, with a median age of 36.6 years (range 18–65). Mean age of onset and duration of diabetes was 13.5 ± 6.5 and 23.6 ± 12.2 years, respectively. Twenty‐one (30%) patients met the metabolic syndrome (MS) criteria. Patients with MS had lower eGDR compared to patients without (5.17 [3.10–8.65] vs. 8.86 [6.82–9.85] mg/kg/min, respectively, p = .003). Median eGDR in patients with nephropathy, retinopathy and neuropathy compared with those without was 6.75 (4.60–8.20) versus 9.53 (8.57–10.3); p < .001, 6.45 (4.60–7.09) versus 9.50 (8.60–10.14); p < .001, 5.56 (4.51–6.81) versus 9.49 [8.19–10.26] mg/kg/min; p < .001, respectively. The eGDR showed an area under the curve of 0.909, 0.879, 0.897 and 0.836 for the discrimination of MS, retinopathy, neuropathy and nephropathy, respectively.

Conclusions

Patients with T1D diabetic complications have higher insulin resistance. The eGDR discriminates patients with chronic diabetic complications and MS. While more ethnic‐specific studies are required, this study suggests the possibility to incorporate eGDR into routine diabetes care.

Body mass index, estimated glucose disposal rate and vascular complications in type 1 diabetes: Beyond glycated haemoglobin

AIMS

To understand the relationship between insulin resistance (IR), assessed as estimated glucose disposal rate (eGDR), and microvascular/macrovascular complications in people with type 1 diabetes.

MATERIALS AND METHODS

Individuals with a confirmed diagnosis of type 1 diabetes were included in this cross-sectional study. BMI was categorised into normal weight (18.0-24.9 kg m^-2 ), overweight (25.0-29.9 kg m^-2 ) and obese groups (≥30.0 kg m^-2 ). We categorised eGDR into four groups: eGDR >8, 6-7.9, 4-5.9 and <4 mg kg^-1  min^-1 . Multiple logistic regression was used to identify associations with vascular complications, after adjusting for relevant confounders.

RESULTS

A total of 2151 individuals with type 1 diabetes were studied. Median [interquartile range (IQR)] age was 41.0 [29.0, 55.0] with diabetes duration of 20.0 [11, 31] years. Odds ratio (OR) for retinopathy and nephropathy in obese compared with normal weight individuals was 1.64 (95% CI: 1.24-2.19; p = 0.001) and 1.62 (95% CI: 1.10-2.39; p = 0.015), while the association with cardiovascular disease just failed to reach statistical significance (OR 1.66 [95% CI: 0.97-2.86; p = 0.066]). Comparing individuals with eGDR ≥8 mg kg^-1  min^-1 and <4 mg kg^-1  min^-1 showed OR for retinopathy, nephropathy and macrovascular disease of 4.84 (95% CI: 3.36-6.97; p < 0.001), 8.35 (95% CI: 4.86-14.34; p < 0.001) and 13.22 (95% CI: 3.10-56.38; p < 0.001), respectively. Individuals with the highest eGDR category (≥8 mg kg^-1  min^-1 ) had the lowest complication rates irrespective of HbA_1c levels.

CONCLUSIONS

Obesity is prevalent in type 1 diabetes and diabetes complications are not only related to glucose control. IR, assessed as eGDR, is strongly associated with both microvascular and macrovascular complications, regardless of HbA_1c levels.

Insulin resistance, diabetic kidney disease, and all-cause mortality in individuals with type 2 diabetes: a prospective cohort study

BACKGROUND

It is unclear whether insulin resistance (IR) contributes to excess mortality in patients with type 2 diabetes independent of diabetic kidney disease (DKD), which is strongly associated with IR and is a major risk factor for cardiovascular disease (CVD), the main cause of death in these individuals. We tested this hypothesis in patients with type 2 diabetes from the Renal Insufficiency And Cardiovascular Events Italian Multicentre Study.

METHODS

This observational, prospective, cohort study enrolled 15,773 patients with type 2 diabetes attending 19 Italian Diabetes Clinics in 2006-2008. Insulin sensitivity was assessed as estimated glucose disposal rate (eGDR), which was validated against the euglycaemic-hyperinsulinemic clamp technique. Vital status on October 31, 2015, was retrieved for 15,656 patients (99.3%). Participants were stratified by eGDR tertiles from T1 (≥ 5.35 mg/kg/min) to T3 (≤ 4.14 mg/kg/min, highest IR).

RESULTS

CVD risk profile was worse in T2 and T3 vs T1. eGDR tertiles were independently associated with micro- and macroalbuminuria and the albuminuric DKD phenotypes (albuminuria with preserved or reduced estimated glomerular filtration rate [eGFR]) as well as with eGFR categories or the nonalbuminuric DKD phenotype. Over a 7.4-year follow-up, unadjusted death rates and mortality risks increased progressively across eGDR tertiles, but remained significantly elevated after adjustment only in T3 vs T1 (age- and gender- adjusted death rate, 22.35 vs 16.74 per 1000 person-years, p < 0.0001, and hazard ratio [HR] adjusted for multiple confounders including DKD, 1.140 [95% confidence interval [CI], 1.049-1.238], p = 0.002). However, eGDR was independently associated with mortality in participants with no DKD (adjusted HR, 1.214 [95% CI, 1.072-1.375], p = 0.002) and in those with nonalbuminuric DKD (1.276 [1.034-1.575], p = 0.023), but not in those with the albuminuric DKD phenotypes. Moreover, the association was stronger in males and in younger individuals and was observed in those without but not with prior CVD, though interaction was significant only for age.

CONCLUSIONS

The proxy of insulin sensitivity eGDR predicts all-cause mortality in type 2 diabetes, independent of confounders including DKD. However, the impact of IR in individuals with albuminuric DKD may be mediated by its relationship with albuminuria.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT00715481, retrospectively registered 15 July 2008.

Double Diabetes: A Growing Problem Requiring Solutions

The growing proportion of type 1 diabetes mellitus (T1DM) patients with clinical features of insulin resistance (IR) has led to the description of a distinctive T1DM subgroup, still unrecognised by current guidelines, called double diabetes, assumingly associated with poorer metabolic phenotype and increased risk of micro- and macrovascular complications. The main goal of identifying double diabetes, estimated to be present in up to half of T1DM patients, is timely implementation of appropriate therapeutic interventions to reduce the increased risk of chronic complications and other adverse metabolic traits associated with this condition. Proposed diagnostic criteria are largely divided into three different groups: family history of type 2 diabetes mellitus (T2DM), obesity/metabolic syndrome, and IR. Estimated glucose disposal rate may prove the most reliable marker of double diabetes. In addition to general measures (diet, physical activity, antihypertensive, and lipid-lowering medications, etc.) and development of new insulin preparations with more hepatic action, double diabetes patients may derive more benefit from agents developed for T2DM. Indeed, such potentially promising agents include glucagon-like peptide-1 receptor agonists, sodium-glucose contrasporter-2 inhibitors, and their combination. We are now awaiting long-term trials assessing metabolic and vascular benefits of these medications in double diabetes.

Variants in HSD11B1 gene modulate susceptibility to diabetes kidney disease and to insulin resistance in type 1 diabetes

BACKGROUND AND AIM

11β-Hydroxysteroid dehydrogenase 1 has been implicated in insulin resistance (IR) in the setting of metabolic disorders, and single nucleotide polymorphisms (SNPs) in its encoding gene (HSD11B1) have been associated with type 2 diabetes and metabolic syndrome. In type 1 diabetes (T1D), IR has been related to the development of chronic complications. We investigated the association of HSD11B1 SNPs with microvascular complications and with IR in a Brazilian cohort of T1D individuals.

MATERIALS AND METHODS

Five SNPs were genotyped in 466 T1D individuals (57% women; median of 37 years old, diabetes duration of 25 years and HbA1c of 8.4%).

RESULTS

The minor allele T of rs11799643 was nominally associated with diabetic retinopathy (OR = 0.52; confidence interval [CI] 95% = 0.28-0.96; P = .036). The minor allele C of rs17389016 was nominally associated with overt diabetic kidney disease (DKD) (OR = 1.90; CI 95% = 1.07-3.37; P = .028). A follow-up study revealed that 29% of the individuals lost ≥5 mL min^-1 × 1.73 m² per year of the estimated glomerular filtration rate (eGFR). In these individuals (eGFR decliners), C allele of rs17389016 was more frequent than in non-decliners (OR = 2.10; CI 95% = 1.14-3.89; P = .018). Finally, minor allele T of rs846906 associated with higher prevalence of arterial hypertension, higher body mass index and waist circumference, thus conferring risk to a lower estimated glucose disposal rate, a surrogate marker of insulin sensitivity (OR = 1.23; CI 95% = 1.06-1.42; P = .004).

CONCLUSION

SNPs in the HSD11B1 gene may confer susceptibility to DKD and to IR in T1D individuals.

Nutrition and Obesity in the Pathogenesis of Youth-Onset Type 1 Diabetes and Its Complications

Since the 1980s, there has been a dramatic rise in the prevalence of overweight and obesity in pediatric populations, in large part driven by sedentary lifestyles and changing dietary patterns with more processed foods. In parallel with the rise in pediatric obesity in the general population, the prevalence of overweight and obesity has increased among children and adolescents with type 1 diabetes. Adiposity has been implicated in a variety of mechanisms both potentiating the risk for type 1 diabetes as well as exacerbating long-term complications, particularly cardiovascular disease. Treatment options targeting the unique needs of obese pediatric patients, both before and after diagnosis of type 1 diabetes, are limited. In this review, we discuss the history of the epidemiology of the obesity epidemic in the context of pediatric type 1 diabetes, highlight the possible role of obesity in type 1 diabetes pathogenesis and review the concept of "double diabetes". The impact of obesity at and after diagnosis will be discussed, including noted differences in clinical and biochemical markers, lipid abnormalities, and long-term cardiovascular complications. Finally, we will review the existing literature on pharmacologic and nutritional interventions as potential treatment strategies for youth with coexisting type 1 diabetes and obesity.

Insulin resistance is associated with preclinical carotid atherosclerosis in patients with type 1 diabetes

AIM

Although insulin resistance (IR) is a growing trait among type 1 diabetes (T1D) population, its relationship with atherosclerosis has been scarcely studied. We assessed the association between IR indexes and carotid atherosclerosis in T1D, a population at high cardiovascular disease (CVD) risk.

MATERIALS AND METHODS

We evaluated 191 participants with T1D and no prior CVD with at least one of the following criteria: ≥40 years old; diabetic nephropathy; or T1D duration ≥10 years harbouring ≥1 additional CVD risk factor. IR was assessed with the metabolic syndrome (MetS) harmonized definition proposed in 2009 and the estimated glucose disposal rate (eGDR), a T1D-specific IR surrogate marker (lower values indicating higher IR). Standardized carotid ultrasonography was performed, recording intima-media thickness (IMT), plaque presence and maximum height of plaque. Comparisons between patients according to their MetS status as well as concerning eGDR values were performed.

RESULTS

The participants' median age was 47.4 (41.1-53.3) years and diabetes duration 25.7 (21.6-32.5) years. Plaque prevalence was higher in patients with greater IR (49.1%, 29.1% and 20%, P = .001, for any plaque according to decreasing eGDR tertiles). Conversely, no statistically significant higher plaque prevalence was found in participants with MetS. In multivariate analyses (adjusted for general- and T1D-specific risk factors, and statin treatment), MetS was associated with neither IMT nor plaque. On the contrary, eGDR was independently related to ≥2 plaques (P = .018) and maximum plaque height (P < .01).

CONCLUSIONS

In T1D, IR assessed through eGDR but not by MetS definition was independently associated with plaque burden, a predictor of CVD.

Insulin resistance is associated with urinary albumin-creatinine ratio in normal weight individuals with hypertension and diabetes: The REACTION study

BACKGROUND

The relationship between albuminuria and insulin resistance (IR) has not been clarified in previous studies. This study was conducted to examine whether IR is associated with albuminuria in subjects with diverse blood pressure and glycometabolism statuses.

METHODS

This study included 34 136 participants whose data were drawn from a cross-sectional survey named the 2011 REACTION study. The participants were divided into six groups. The urinary albumin-creatinine ratio (UACR) and glomerular filtration rate (GFR) were used as markers of chronic kidney disease (CKD). Variance tests and logistic regression models were performed for homeostatic model assessment of insulin resistance (HOMA-IR) in relation to UACR and eGFR.

RESULTS

First, UACR levels and HOMA-IR exhibited a positive correlation among participants (P < 0.05), and a negative correlation existed between GFR and HOMA-IR (P < 0.05). Second, in the hypertension with diabetes group, in individuals whose body mass index (BMI) was 18.5-24.0 kg/m² , age was 50-60 years old, low density lipoprotein cholesterol (LDL-C) was 2.6-3.4 mmol/L or high density lipoprotein cholesterol (HDL-C) was 0.9-1.55 mmol/L, HOMA-IR was positively associated with UACR (P < 0.05). However, there was a negative correlation between GFR and HOMA-IR in the hypertension with diabetes group in individuals whose BMI was 18.5-24.0 kg/m² or whose age was over 65 years old (P < 0.05).

CONCLUSIONS

In the context of different blood pressure and glycometabolism statuses, the positive correlation between UACR levels and HOMA-IR was affected by BMI, age, LDL-C, HDL-C, and GFR. In patients with hypertension and diabetes, the early detection and intervention of IR and related risk factors in patients with normal BMI may reduce the occurrence of microalbuminuria and delay the progression of CKD.

Screening for non-alcoholic fatty liver disease in type 2 diabetes using non-invasive scores and association with diabetic complications

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is prevalent in patients with type 2 diabetes. Here, we estimate the proportion of patients with type 2 diabetes that should be referred to hepatologists according to the European Association for the Study of the Liver (EASL)-European Association for the Study of Diabetes (EASD)-European Association for the Study of Obesity (EASO) Guidelines and evaluate the association between non-invasive biomarkers of steatosis and fibrosis and diabetic complications.

RESEARCH DESIGN AND METHODS

This is a retrospective analysis of type 2 diabetes patients who attended on a regular basis our diabetes clinic between 2013 and 2018 (n=2770). Steatosis was assessed using Fatty Liver Index (FLI), Hepatic Steatosis Index and NAFLD Ridge Score and fibrosis using NAFLD Fibrosis Score (NFS), Fibrosis-4 (FIB-4), aspartate aminotransferase (AST) to platelet ratio index (APRI) and AST/alanine aminotransferase (ALT) ratio. Outcome measures were altered albumin excretion rate (AER), chronic kidney disease (CKD) and cardiovascular disease (CVD).

RESULTS

The prevalence of advanced fibrosis varied from 1% (APRI) to 33% (NFS). The application of the guidelines using a sequential combination of FLI and FIB-4 would lead to referral of 28.3% of patients when using standard FIB-4 cut-offs, while this number dropped to 13.4% when age-adjusted FIB-4 thresholds were applied. A higher prevalence of altered AER was associated with liver steatosis (FLI: OR: 3.49; 95% CI 2.05 to 5.94, p<0.01), whereas liver fibrosis was associated with CKD (FIB-4: OR: 6.39; 95% CI 4.05 to 10.08, p<0.01) and CVD (FIB-4: OR: 2.62; 95% CI 1.69 to 4.04, p<0.01).

CONCLUSIONS

While specific fibrosis scores identify different proportion of patients with advanced fibrosis, the use of age-adjusted FIB-4 cut-offs leads to a drop in gray-zone results, making referrals to hepatologists more sustainable. Interestingly non-invasive biomarkers were consistently associated with a different pattern of diabetic complications.

SHIPping out diabetes-Metformin, an old friend among new SHIP2 inhibitors

SHIP2 (Src homology 2 domain‐containing inositol 5′‐phosphatase 2) belongs to the family of 5′‐phosphatases. It regulates the phosphoinositide 3‐kinase (PI3K)‐mediated insulin signalling cascade by dephosphorylating the 5′‐position of PtdIns(3,4,5)P3 to generate PtdIns(3,4)P2, suppressing the activity of the pathway. SHIP2 mouse models and genetic studies in human propose that increased expression or activity of SHIP2 contributes to the pathogenesis of the metabolic syndrome, hypertension and type 2 diabetes. This has raised great interest to identify SHIP2 inhibitors that could be used to design new treatments for metabolic diseases. This review summarizes the central mechanisms associated with the development of diabetic kidney disease, including the role of insulin resistance, and then moves on to describe the function of SHIP2 as a regulator of metabolism in mouse models. Finally, the identification of SHIP2 inhibitors and their effects on metabolic processes in vitro and in vivo are outlined. One of the newly identified SHIP2 inhibitors is metformin, the first‐line medication prescribed to patients with type 2 diabetes, further boosting the attraction of SHIP2 as a treatment target to ameliorate metabolic disorders.

Impaired glucose tolerance and albuminuria in patients with chronic heart failure: a subanalysis of the SUPPORT trial

AIMS

The study aims to evaluate the prognostic significance of impaired glucose tolerance (IGT) with reference to albuminuria in patients with chronic heart failure (CHF).

METHODS AND RESULTS

We examined 535 CHF patients (mean 66 years, women 25%) in the control arm of our SUPPORT trial, in which we examined additive impact of olmesartan in hypertensive patients with symptomatic CHF treated with β-blockers and/or angiotensin-converting enzyme inhibitors. We examined the association between glycaemic abnormality (assessed by 75 g of oral glucose tolerance test) and albuminuria for a composite outcome of all-cause death, myocardial infarction, stroke, and HF hospitalization. IGT patients (N = 113, mean 67.2 years) were older and more frequently treated with β-blockers compared with those with normal glucose regulation (N = 142, mean 64.0 years) and those with diabetes mellitus (N = 280, mean 65.7 years). Multivariable Cox proportional hazard models revealed that, as compared with normal glucose regulation (NGR), IGT was associated with increased risk of the outcome when complicated by albuminuria [hazard ratio (HR) 2.25; 95% confidence interval (CI) 1.14-4.42; P = 0.019] but not when uncomplicated by albuminuria (HR 0.76; 95% CI 0.35-1.60, P = 0.47) (P for interaction = 0.041). This was also the case for diabetes mellitus and albuminuria (HR 2.06; 95% CI 1.17-3.61; P = 0.012). Among IGT patients without albuminuria, 21 (29%) developed albuminuria at 1-year visit, which was again associated with poor prognosis (HR 7.36; 95% CI 1.39-38.98, P = 0.019).

CONCLUSIONS

These results indicate that IGT is associated with poor prognosis when complicated by albuminuria in CHF patients, demonstrating the importance of combined early stages of glucose intolerance and renal dysfunction in the management of CHF.

Double diabetes: A distinct high-risk group?

The term double diabetes (DD) has been used to refer to individuals with type 1 diabetes (T1D) who are overweight, have a family history of type 2 diabetes and/or clinical features of insulin resistance. Several pieces of evidence indicate that individuals who display features of DD are at higher risk of developing future diabetes complications, independently of average glucose control, measured as glycated haemoglobin (HbA1c) concentration. Given the increased prevalence of individuals with features of DD, pragmatic criteria are urgently required to identify and stratify this group, which will help with subsequent implementation of more effective personalized interventions. In this review, we discuss the potential criteria for the clinical identification of individuals with DD, highlighting the strengths and weaknesses of each definition. We also cover potential mechanisms of DD and how these contribute to increased risk of diabetes complications. Special emphasis is placed on the role of estimated glucose disposal rate (eGDR) in the diagnosis of DD, which can be easily incorporated into clinical practice and is predictive of adverse clinical outcome. In addition to the identification of individuals with DD, eGDR has potential utility in monitoring response to different interventions. T1D is a more heterogeneous condition than initially envisaged, and those with features of DD represent a subgroup at higher risk of complications. Pragmatic criteria for the diagnosis of individuals with DD will help with risk stratification, allowing a more personalized and targeted management strategy to improve outcome and quality of life in this population.

Does diabetes prevention translate into reduced long-term vascular complications of diabetes?

The global epidemic of type 2 diabetes has prompted numerous studies and public health efforts to reduce its development. A variety of interventions, including lifestyle modifications and pharmacological agents directed at ameliorating the major risk factors for type 2 diabetes, are of proven efficacy in reducing the development of type 2 diabetes in people with impaired glucose tolerance. While prevention of the hyperglycaemia characteristic of diabetes is arguably an important, clinically relevant outcome, a more compelling outcome with greater clinical significance is the prevention or reduction of the relatively diabetes-specific microvascular and less-specific cardiovascular disease (CVD) complications associated with diabetes. These complications cause the majority of morbidity and excess mortality associated with diabetes. Any reduction in diabetes should, logically, also reduce the occurrence of its long-term complications; however, most diabetes prevention trials have not been of sufficient duration to allow such an evaluation. The limited long-term data, largely from the Da Qing Diabetes Prevention Study (DQDPS) and the Diabetes Prevention Program (DPP) and their respective follow-up studies (DQDPOS and DPPOS), suggest a reduction in microvascular complications and amelioration of CVD risk factors. Only the DQDPOS and Study to Prevent Non-Insulin-Dependent Diabetes Mellitus (STOP-NIDDM) studies have shown a reduction in CVD events and only DQDPOS has demonstrated a decrease in CVD and overall mortality. While these limited data are promising, whether diabetes prevention directly reduces complication-related morbidity and mortality remains unclear. Longer follow-up of prevention studies is needed to supplement the limited current clinical trial data, to help differentiate the effects of diabetes prevention itself from the means used to reduce diabetes development and to understand the balance among benefits, risks and costs of prevention.

Carbohydrate Restriction in Type 1 Diabetes: A Realistic Therapy for Improved Glycaemic Control and Athletic Performance?

Around 80% of individuals with Type 1 diabetes (T1D) in the United States do not achieve glycaemic targets and the prevalence of comorbidities suggests that novel therapeutic strategies, including lifestyle modification, are needed. Current nutrition guidelines suggest a flexible approach to carbohydrate intake matched with intensive insulin therapy. These guidelines are designed to facilitate greater freedom around nutritional choices but they may lead to higher caloric intakes and potentially unhealthy eating patterns that are contributing to the high prevalence of obesity and metabolic syndrome in people with T1D. Low carbohydrate diets (LCD; <130 g/day) may represent a means to improve glycaemic control and metabolic health in people with T1D. Regular recreational exercise or achieving a high level of athletic performance is important for many living with T1D. Research conducted on people without T1D suggests that training with reduced carbohydrate availability (often termed "train low") enhances metabolic adaptation compared to training with normal or high carbohydrate availability. However, these "train low" practices have not been tested in athletes with T1D. This review aims to investigate the known pros and cons of LCDs as a potentially effective, achievable, and safe therapy to improve glycaemic control and metabolic health in people with T1D. Secondly, we discuss the potential for low, restricted, or periodised carbohydrate diets in athletes with T1D.

Insulin Resistance in Adults with Type 1 Diabetes is Associated with Lower Vitamin D Serum Concentration

AIM

Type 1 diabetes mellitus (T1DM) is a disease characterized by an absolute deficiency of endogenous insulin secretion. Insulin resistance (IR) may develop among patients with T1DM. Vitamin D deficiency was reported to be a risk factor in the development of IR. The aim of the study was to assess the relationship between serum concentrations of 25-hydroxyvitamin D (25(OH)D) and IR among patients with T1DM.

METHODS

The test group consisted of 110 adult patients [males=65 (59%)] with T1DM. Participants were recruited in Poland between 1^st October and 30^th April in 2015/2016 and 2016/2017. VD serum level was assessed by ELISA array. IR was assessed by estimated Glucose Disposal Rate (eGDR).

RESULTS

In the study group 21 (19%) patients were recognized as IR according to eGDR cut-offs (<7.5 mg/kg/min), 52 (47.3%) patients had VD deficiency (25(OH)D<20 ng/ml), 16 (14.5%) patients had 25(OH)D<10 ng/ml. Only 6 (5%) participants reported VD supplementation. Patients with IR, according to eGDR cut-off revealed significantly lower 25(OH)D serum level 15.7 (9.2-28.4) vs. 22.1 (13.0-38.4) ng/ml; p=0.04 as compared to patients without IR. R Spearman analysis found a positive relationship between VD and eGDR (Rs=0.27; p<0.01). Logistic regression analysis revealed significant relationship between the presence of IR and VD serum level/presence of 25(OH)D serum level below 10 ng/ml, both models adjusted to sex, age, BMI, LDL and triglycerides, accordingly (OR=0.95, CI: 0.90-0.99; p=0.04) and (OR=4.19, CI: 1.04-16.93; p=0.04).

CONCLUSION

The serum concentration of Vitamin D is negatively associated with insulin resistance in patients with T1DM and may have clinical implications.

Effects of metreleptin on proteinuria in patients with lipodystrophy

CONTEXT

Patients with lipodystrophy have high prevalence of proteinuria.

OBJECTIVE

To assess kidney disease in patients with generalized (GLD) versus partial lipodystrophy (PLD), and effects metreleptin on proteinuria in patients with lipodystrophy.

DESIGN/SETTING/PATIENTS/INTERVENTION

Prospective, open-label studies of metreleptin treatment in patients with GLD and PLD at the National Institutes of Health, Bethesda, MD.

OUTCOME MEASURES

24-hour urinary albumin and protein excretion rates, estimated glomerular filtration rate (eGFR), and creatinine clearance (CrCl) were measured at baseline and during up to 24 months of metreleptin treatment. Patients with increases in medications affecting outcome measures were excluded.

RESULTS

At baseline, patients with GLD had significantly greater albuminuria, proteinuria, eGFR, and CrCl compared to patients with PLD. CrCl was above the normal range in 69% of patients with GLD, and 39% with PLD (P=0.02). With up to 24 months of metreleptin treatment, there were significant reductions in albuminuria and proteinuria in patients with GLD, but not in those with PLD. No changes in eGFR or CrCl were observed in patients with GLD or PLD during metreleptin treatment.

CONCLUSIONS

Patients with GLD had significantly greater proteinuria than those with PLD, which improved with metreleptin treatment. The mechanisms leading to proteinuria in lipodystrophy and improvements in proteinuria with metreleptin are not clear. Hyperfiltration was also more common in GLD versus PLD but did not change with metreleptin.

Metformin increases glucose uptake and acts renoprotectively by reducing SHIP2 activity

Metformin, the first-line drug to treat type 2 diabetes (T2D), inhibits mitochondrial glycerolphosphate dehydrogenase in the liver to suppress gluconeogenesis. However, the direct target and the underlying mechanisms by which metformin increases glucose uptake in peripheral tissues remain uncharacterized. Lipid phosphatase Src homology 2 domain-containing inositol-5-phosphatase 2 (SHIP2) is upregulated in diabetic rodent models and suppresses insulin signaling by reducing Akt activation, leading to insulin resistance and diminished glucose uptake. Here, we demonstrate that metformin directly binds to and reduces the catalytic activity of the recombinant SHIP2 phosphatase domain in vitro. Metformin inhibits SHIP2 in cultured cells and in skeletal muscle and kidney of db/db mice. In SHIP2-overexpressing myotubes, metformin ameliorates reduced glucose uptake by slowing down glucose transporter 4 endocytosis. SHIP2 overexpression reduces Akt activity and enhances podocyte apoptosis, and both are restored to normal levels by metformin. SHIP2 activity is elevated in glomeruli of patients with T2D receiving nonmetformin medication, but not in patients receiving metformin, compared with people without diabetes. Furthermore, podocyte loss in kidneys of metformin-treated T2D patients is reduced compared with patients receiving nonmetformin medication. Our data unravel a novel molecular mechanism by which metformin enhances glucose uptake and acts renoprotectively by reducing SHIP2 activity.-Polianskyte-Prause, Z., Tolvanen, T. A., Lindfors, S., Dumont, V., Van, M., Wang, H., Dash, S. N., Berg, M., Naams, J.-B., Hautala, L. C., Nisen, H., Mirtti, T., Groop, P.-H., Wähälä, K., Tienari, J., Lehtonen, S. Metformin increases glucose uptake and acts renoprotectively by reducing SHIP2 activity.

Estimated glucose disposal rate predicts mortality in adults with type 1 diabetes

AIMS

This study aimed to investigate the association between insulin resistance as determined by the estimated glucose disposal rate (eGDR), and survival in adults with type 1 diabetes (T1D) in Sweden.

MATERIAL AND METHODS

Using the Swedish National Diabetes Register, indviduals with T1D were included from January 1, 2005 to December 31, 2012. Outcomes were retrieved from National healthcare registers. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated for the associations between eGDR (mg/kg/min) categorized into <4, 4 to 5.99, 6 to 7.99, and ≥8 (reference) and outcomes. Relative survival methods were used to compare survival to a matched Swedish reference population.

RESULTS

Among 17 050 included individuals with T1D, 10.5%, 20.2%, 20.5% and 48.9% had an eGDR of <4, 4 to 5.99, 6 to 7.99, and ≥8, respectively. Individuals with an eGDR <8 were older and had more comorbidities. During a median follow-up of 7.1 years, there were 946 (6%) deaths; 264 (15%), 367 (11%), 195 (6%) and 120 (1%) deaths occurred in individuals with an eGDR of <4, 4 to 5.99, 6 to 7.99 and ≥8, respectively. After adjustment for a wealth of different covariates including diabetes duration, age, sex and renal function, individuals with an eGDR <4, 4 to 5.99, and 6 to 7.99 had an increased risk of death compared to those with an eGDR ≥8 (adjusted HRs, 95% CIs, P values: 2.78, 2.04 to 3.77, <.001; 1.92, 1.49 to 2.46, <.001; 1.73, 1.34 to 2.21, <.001). Survival in individuals with an eGDR ≥8 was equal to a matched general population.

CONCLUSIONS

There is a strong association between eGDR and all-cause mortality, as well as cardiovascular mortality, in individuals with T1D. Our findings may guide preventive measures by improving risk assessment in individuals with T1D.

TG/HDL-C ratio and visceral adiposity index may be useful in assessment of insulin resistance in adults with type 1 diabetes in clinical practice

BACKGROUND

Insulin resistance (IR) is an important clinical issue in patients with type 1 diabetes due to worse metabolic control and risk of development of chronic complications.

OBJECTIVE

The aim of the study was to evaluate simple and easily available parameters as indirect markers of IR in adults with type 1 diabetes and correlate it with the results of hyperinsulinemic-euglycemic clamp.

METHODS

The study included 88 patients (62 men), aged 34.1 ± 6.5 years, with type 1 diabetes with a median disease duration of 8 (7-13) years and mean HbA1c of 7.6 ± 1.5%. Tissue sensitivity to insulin was assessed on the basis of glucose distribution rate (GDR) obtained in the course of hyperinsulinemic-euglycemic clamp. In addition, indirect markers of IR, such as estimated GDR, presence of features of metabolic syndrome, visceral adiposity index (VAI), and the triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C) ratio, were evaluated.

RESULTS

In the study group, IR defined as GDR <4 mg/kg/min was observed in 33 (37.5%) patients. Group with IR had significantly higher postprandial glycemia (9.1 ± 2.0 vs 8.4 ± 1.1 mmol/L, P = .04), serum TG level (1.11 [0.75-1.92] vs 0.85 [0.60-1.08] mmol/L, P = .001), lower HDL-C level (1.59 ± 0.38 vs 1.8 ± 0.5 mmol/L, P = .02), higher TG/HDL-C ratio (1.60 [1.00-3.13] vs 1.05 [0.62-1.53], P = .001), and higher VAI (2.61 [1.31-4.25] vs 1.56 [0.96-2.25], P = .002). Significant relationship between GDR and TG/HDL-C ratio and VAI, adjusted for age, sex, HbA1c, and duration of diabetes was revealed (respectively, odds ratio 1.90 [95% confidence interval 1.15-3.15], P = .01 and odds ratio 1.47 [95% confidence interval 1.06-2.04], P = .01).

CONCLUSIONS

TG/HDL-C ratio and VAI appear to be clinically useful tools to assess IR in adults with type 1 diabetes.

The Evolving Importance of Insulin Signaling in Podocyte Health and Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide, occuring in approximately one-third of diabetic patients. One of the earliest hallmarks of DKD is albuminuria, often occurring following disruptions to the glomerular filtration barrier. Podocytes are highly specialized cells with a central role in filtration barrier maintenance; hence, podocyte dysfunction is a major cause of albuminuria in many settings, including DKD. Numerous studies over the last decade have highlighted the importance of intact podocyte insulin responses in the maintenance of podocyte function. This review summarizes our current perspectives on podocyte insulin signaling, highlighting evidence to support the notion that dysregulated podocyte insulin responses contribute toward podocyte damage, particularly during the pathogenesis of DKD.

Predictors of early renal function decline in adults with Type 1 diabetes: the Coronary Artery Calcification in Type 1 Diabetes and the Pittsburgh Epidemiology of Diabetes Complications studies

AIM

Diabetic kidney disease is one of the leading complications of Type 1 diabetes, but its prediction remains a challenge. We examined predictors of rapid decline in estimated GFR (eGFR) in two Type 1 diabetes cohorts: the Coronary Artery Calcification in Type 1 Diabetes (CACTI) and the Pittsburgh Epidemiology of Diabetes Complications (EDC).

METHODS

A select subset of participants (CACTI: n = 210 and EDC: n = 98) diagnosed before 17 years of age with Type 1 diabetes duration ≥ 7 years, and follow-up data on eGFR by CKD-EPI creatinine for up to 8 years were included in the analyses. Early renal function decline was defined as annual decline in eGFR ≥ 3 ml/min/1.73 m² , and normal age-related decline as eGFR ≤ 1 ml/min/1.73 m² . Parallel logistic regression models were constructed in the two cohorts.

RESULTS

Early renal function decline incidence was 36% in CACTI and 41% in EDC. In both cohorts, greater baseline eGFR (CACTI: OR 3.12, 95% CI 1.97-5.05; EDC: OR 1.92, 95% CI 1.17-3.15 per 10 ml/min/1.73 m² ) and log albumin-to-creatinine (ACR) (CACTI: OR 3.24, 95% CI 1.80-5.83; EDC: OR 1.87, 95% CI 1.18-2.96 per 1 unit) predicted greater odds of early renal function decline in fully adjusted models. Conversely, ACE inhibition predicted lower odds of early renal function decline in women in CACTI, but similar relationships were not observed in women in EDC.

CONCLUSIONS

A substantial proportion of people with Type 1 diabetes in the EDC and CACTI cohorts experienced early renal function decline over time. ACE inhibition appeared to be protective only in women in CACTI where the prevalence of its use was twofold higher compared with the EDC.

Prolonged exposure of mouse and human podocytes to insulin induces insulin resistance through lysosomal and proteasomal degradation of the insulin receptor

AIMS/HYPOTHESIS

Podocytes are insulin-responsive cells of the glomerular filtration barrier and are key in preventing albuminuria, a hallmark feature of diabetic nephropathy. While there is evidence that a loss of insulin signalling to podocytes is detrimental, the molecular mechanisms underpinning the development of podocyte insulin resistance in diabetes remain unclear. Thus, we aimed to further investigate podocyte insulin responses early in the context of diabetic nephropathy.

METHODS

Conditionally immortalised human and mouse podocyte cell lines and glomeruli isolated from db/db DBA/2J mice were studied. Podocyte insulin responses were investigated with western blotting, cellular glucose uptake assays and automated fluorescent imaging of the actin cytoskeleton. Quantitative (q)RT-PCR was employed to investigate changes in mRNA. Human cell lines stably overproducing the insulin receptor (IR) and nephrin were also generated, using lentiviral constructs.

RESULTS

Podocytes exposed to a diabetic environment (high glucose, high insulin and the proinflammatory cytokines TNF-α and IL-6) become insulin resistant with respect to glucose uptake and activation of phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signalling. These podocytes lose expression of the IR as a direct consequence of prolonged exposure to high insulin concentrations, which causes an increase in IR protein degradation via a proteasome-dependent and bafilomycin-sensitive pathway. Reintroducing the IR into insulin-resistant human podocytes rescues upstream phosphorylation events, but not glucose uptake. Stable expression of nephrin is also required for the insulin-stimulated glucose uptake response in podocytes and for efficient insulin-stimulated remodelling of the actin cytoskeleton.

CONCLUSIONS/INTERPRETATION

Together, these results suggest that IR degradation, caused by high levels of insulin, drives early podocyte insulin resistance, and that both the IR and nephrin are required for full insulin sensitivity of this cell. This could be highly relevant for the development of nephropathy in individuals with type 2 diabetes, who are commonly hyperinsulinaemic in the early phases of their disease.

Insulin resistance correlates with maculopathy and severity of retinopathy in young adults with Type 1 Diabetes Mellitus

AIMS

To assess the relationship between insulin resistance (IR), retinopathy and maculopathy in young adults with Type 1 diabetes mellitus.

METHODS

A cross-sectional study at a regional Australian tertiary hospital. Retinal pathology, assessed by colour fundus photography, was correlated with two surrogate measures of IR: estimated Glucose Disposal Rate (eGDR) and Insulin Sensitivity Score (ISS), where lower scores reflect greater IR.

RESULTS

107 patients were recruited, with mean age 24.7years, 53% male, and mean duration of disease 10.8years. Mean eGDR scores (5.6vs 8.0 p<0.001) and ISS (4.7vs 7.9, p<0.001) were lower in subjects having at least moderate non-proliferative diabetic retinopathy (NPDR; relative to nil/mild-NPDR). Similarly, mean eGDR (4.2vs 6.2, p=0.001) and ISS (3.8vs 6.1, p=0.003) were lower in patients with maculopathy. Multivariate logistic regression modelling was used to control for confounding. For retinopathy severity, a unit increase in eGDR or ISS (representing lower IR) was associated with a 50% decrease in odds of moderate-NPDR or worse (eGDR OR 0.5, 95%CI 0.32-0.77, p=0.002; ISS OR 0.49, 95%CI 0.29-0.84, p=0.01). A unit increase in eGDR or ISS was associated with a 46-56% decrease in odds of maculopathy (eGDR OR 0.54, 95%CI 0.37-0.81, p=0.003; ISS OR 0.44, 95%CI 0.22-0.88, p=0.02).

CONCLUSIONS

IR correlates with more severe retinopathy in young adults with Type 1DM. This is the first description of a correlation between IR and maculopathy in Type 1DM, warranting further evaluation. Prospective studies examining whether reducing IR can improve microvascular complications are required.

Comparison of adjunctive therapy with metformin and acarbose in patients with Type-1 diabetes mellitus

Objective:

All the aforementioned data have stimulated interest in studying other potential therapies for T1DM including noninsulin pharmacological therapies. The present study attempts to investigate the effect of adjunctive therapy with metformin and acarbose in patients with Type-1 diabetes mellitus.

Method:

In a single-center, placebo-controlled study (IRCT201102165844N1) we compared the results of two clinical trials conducted in two different time periods on 40 patients with Type-1 diabetes mellitus. In the first section, metformin was given to the subjects. After six months, metformin was replaced with acarbose in the therapeutic regimen. In both studies, subjects were checked for their BMI, FBS, HbA1C, TGs, Cholesterol, LDL, HDL, 2hpp, unit of NPH and regular insulin variations.

Results:

Placebo-controlled evaluation of selected factors has showna significant decrease in FBS and TG levels in the metformin group during follow up but acarbose group has shown substantial influence on two hour post prandial (2hpp) and regular insulin intake decline. Moreover, Comparison differences after intervention between two test groups has shown that metformin has had superior impact on FBS and HbA1C decline in patients. Nonetheless, acarbose treatment had noteworthy influence on 2hpp, TGs, Cholesterol, LDL, and regular insulin intake control.

Conclusion:

The results of this experiment demonstrate that the addition of acarbose or metformin to patients with Type-1 diabetes mellitus who are controlled with insulin is commonly well tolerated and help to improve metabolic control in patients.

Cardiovascular complications of type 1 diabetes: update on the renal link

AIMS

Despite recent findings of increased life expectancy among individuals with type 1 diabetes, mortality remains greatly increased compared to the general population. As this is largely the result of cardiovascular and renal complications, we aimed to review recent findings surrounding these diseases in type 1 diabetes.

METHODS

We reviewed published findings concerning the cardiovascular complications of type 1 diabetes, with a particular focus on links with renal disease.

RESULTS

The cardiovascular and renal complications of type 1 diabetes share many features including insulin resistance, oxidative damage, and genetic associations with the Haptoglobin genotype, and both are strongly affected by glycemic control.

CONCLUSIONS

Although current knowledge on predictors of type 1 diabetes cardiovascular and renal complications has increased, further investigation is required to understand the mechanisms leading to cardio-renal complications in this population.

Insulin resistance, role of metformin and other non-insulin therapies in pediatric type 1 diabetes

Type 1 diabetes mellitus (T1DM) in youth is a challenging chronic medical condition. Its management should address not only the glycemic control but also insulin resistance and cardiovascular disease risk factors which are increasingly recognized to be present in youth with TID. Current knowledge on the mechanisms of insulin resistance in T1DM is reviewed. The use of adjunctive therapies that are beneficial to achieve adequate glycemic control while mitigating the effects of insulin resistance are discussed with a focus on metformin therapy and an overview of other new pharmacologic agents.

DBA2J db/db mice are susceptible to early albuminuria and glomerulosclerosis that correlate with systemic insulin resistance

Diabetic nephropathy (DN) is the leading cause of kidney failure in the world. To understand important mechanisms underlying this condition, and to develop new therapies, good animal models are required. In mouse models of type 1 diabetes, the DBA/2J strain has been shown to be more susceptible to develop kidney disease than other common strains. We hypothesized this would also be the case in type 2 diabetes. We studied db/db and wild-type (wt) DBA/2J mice and compared these with the db/db BLKS/J mouse, which is currently the most widely used type 2 DN model. Mice were analyzed from age 6 to 12 wk for systemic insulin resistance, albuminuria, and glomerular histopathological and ultrastructural changes. Body weight and nonfasted blood glucose were increased by 8 wk in both genders, while systemic insulin resistance commenced by 6 wk in female and 8 wk in male db/db DBA/2J mice. The urinary albumin-to-creatinine ratio (ACR) was closely linked to systemic insulin resistance in both sexes and was increased ~50-fold by 12 wk of age in the db/db DBA/2J cohort. Glomerulosclerosis, foot process effacement, and glomerular basement membrane thickening were observed at 12 wk of age in db/db DBA/2J mice. Compared with db/db BLKS/J mice, db/db DBA/2J mice had significantly increased levels of urinary ACR, but similar glomerular histopathological and ultrastructural changes. The db/db DBA/2J mouse is a robust model of early-stage albuminuric DN, and its levels of albuminuria correlate closely with systemic insulin resistance. This mouse model will be helpful in defining early mechanisms of DN and ultimately the development of novel therapies.

Diabetic Nephropathy: Perspective on Novel Molecular Mechanisms

Diabetes mellitus (DM) is the major cause of end-stage renal disease (ESRD) globally, and novel treatments are urgently needed. Current therapeutic approaches for diabetic nephropathy (DN) are focussing on blood pressure control with inhibitors of the renin-angiotensin-aldosterone system, on glycaemic and lipid control, and life-style changes. In this review, we highlight new molecular insights aiding our understanding of the initiation and progression of DN, including glomerular insulin resistance, dysregulation of cellular substrate utilisation, podocyte-endothelial communication, and inhibition of tubular sodium coupled glucose reabsorption. We believe that these mechanisms offer new therapeutic targets that can be exploited to develop important renoprotective treatments for DN over the next decade.

High Glucose Impairs Insulin Signaling in the Glomerulus: An In Vitro and Ex Vivo Approach

Objective

Chronic hyperglycaemia, as seen in type II diabetes, results in both morphological and functional impairments of podocytes in the kidney. We investigated the effects of high glucose (HG) on the insulin signaling pathway, focusing on cell survival and apoptotic markers, in immortalized human glomerular cells (HGEC; podocytes) and isolated glomeruli from healthy rats.

Methods and Findings

HGEC and isolated glomeruli were cultured for various time intervals under HG concentrations in the presence or absence of insulin. Our findings indicated that exposure of HGEC to HG led to downregulation of all insulin signaling markers tested (IR, p-IR, IRS-1, p-Akt, p-Fox01,03), as well as to increased sensitivity to apoptosis (as seen by increased PARP cleavage, Casp3 activation and DNA fragmentation). Short insulin pulse caused upregulation of insulin signaling markers (IR, p-IR, p-Akt, p-Fox01,03) in a greater extent in normoglycaemic cells compared to hyperglycaemic cells and for the case of p-Akt, in a PI3K-dependent manner. IRS-1 phosphorylation of HG-treated podocytes was negatively regulated, favoring serine versus tyrosine residues. Prolonged insulin treatment caused a significant decrease of IR levels, while alterations in glucose concentrations for various time intervals demonstrated changes of IR, p-IR and p-Akt levels, suggesting that the IR signaling pathway is regulated by glucose levels. Finally, HG exerted similar effects in isolated glomeruli.

Conclusions

These results suggest that HG compromises the insulin signaling pathway in the glomerulus, promoting a proapoptotic environment, with a possible critical step for this malfunction lying at the level of IRS-1 phosphorylation; thus we herein demonstrate glomerular insulin signaling as another target for investigation for the prevention and/ or treatment of diabetic nephropathy.

The dose-response effect of insulin sensitivity on albuminuria in children according to diabetes type

BACKGROUND

Insulin resistance is associated with microalbuminuria among youth with diabetes mellitus. We sought to determine the dose-response effect of insulin sensitivity (IS) on the magnitude of albuminuria and whether there is a threshold below which urine albumin excretion increases.

METHODS

These analyses included participants from the SEARCH for Diabetes in Youth Study with incident diabetes who completed a baseline study visit (n = 2988). We estimated IS using a validated equation incorporating waist circumference, HbA1C, and fasting serum triglycerides. Multivariate regression analyses were performed to assess the effect of IS on urine albumin creatinine ratio (UACR), stratified by diabetes type. The IS threshold was then determined using segmented regressions within each diabetes type and incorporated into the multivariate model.

RESULTS

There was an association between IS and UACR in type 2 diabetes only (beta = -0.39; p < 0.001). There was strong statistical evidence for a threshold effect of IS score on UACR in the group of youth with type 2 (beta = 0.40; p < 0.001) but not type 1 diabetes (p = 0.3).

CONCLUSIONS

In cross-sectional analyses, there is a negative association between IS and UACR in youth with type 2 but not type 1 diabetes, and this association likely includes a threshold effect of IS on UACR.

Selective Insulin Resistance in the Kidney

Insulin resistance has been characterized as attenuation of insulin sensitivity at target organs and tissues, such as muscle and fat tissues and the liver. The insulin signaling cascade is divided into major pathways such as the PI3K/Akt pathway and the MAPK/MEK pathway. In insulin resistance, however, these pathways are not equally impaired. For example, in the liver, inhibition of gluconeogenesis by the insulin receptor substrate (IRS) 2 pathway is impaired, while lipogenesis by the IRS1 pathway is preserved, thus causing hyperglycemia and hyperlipidemia. It has been recently suggested that selective impairment of insulin signaling cascades in insulin resistance also occurs in the kidney. In the renal proximal tubule, insulin signaling via IRS1 is inhibited, while insulin signaling via IRS2 is preserved. Insulin signaling via IRS2 continues to stimulate sodium reabsorption in the proximal tubule and causes sodium retention, edema, and hypertension. IRS1 signaling deficiency in the proximal tubule may impair IRS1-mediated inhibition of gluconeogenesis, which could induce hyperglycemia by preserving glucose production. In the glomerulus, the impairment of IRS1 signaling deteriorates the structure and function of podocyte and endothelial cells, possibly causing diabetic nephropathy. This paper mainly describes selective insulin resistance in the kidney, focusing on the proximal tubule.

Estimated insulin sensitivity predicts incident micro- and macrovascular complications in adults with type 1 diabetes over 6 years: the coronary artery calcification in type 1 diabetes study

OBJECTIVE

Reduced insulin sensitivity (IS) is well documented in type 1 diabetes (T1D) and may contribute to vascular complications. We examined the association of estimated IS (eIS) with incident macro- and microvascular complications in adults with T1D in the prospective CACTI study.

METHODS

Participants (N=652) were 19-56 years old at baseline and re-examined 6.2±0.6years later. Urinary albumin excretion was measured, and categorized as microalbuminuria or greater. Diabetic retinopathy (DR) was based on self-reported history, proliferative DR (PDR) as history of laser eye therapy and coronary artery calcium (CAC) was measured using electron-beam CT. Progression of CAC was defined as a change in the square root transformed CAC volume score of ≥2.5. IS was estimated (eIS) by an equation derived from clamp studies. Predictors of each complication were examined using stepwise logistic regression and subjects with complications at baseline excluded. Age, T1D duration, sex, HbA1c, SBP, LDL-C, and eIS were considered for inclusion.

RESULTS

Greater eIS at baseline predicted lower odds of developing albuminuria (OR: 0.67, 95% CI 0.51-0.88), DR (OR 0.79, 0.64-0.97), PDR (OR: 0.76, 0.57-0.99) and CACp (OR: 0.71, 0.60-0.85) in multivariable models.

CONCLUSIONS

Greater eIS conferred protection from the development of vascular complications over 6-years in T1D.

Association between obesity measures and albuminuria: A population-based study

AIMS

The effects of obesity on the micro vascular diseases have drawn much attention. The aim of the study was to investigate the relationship between obesity measures and albuminuria in Chinese population.

METHODS

We conducted a population-based cross-sectional study in 8600 subjects aged 40 years or older from a community in Guangzhou. Urinary albumin excretion and creatinine were measured and urinary albumin-to-creatinine ratio (ACR) was calculated as urinary albumin divided by creatinine. Low-grade albuminuria was classified as the highest quartile of ACR in participants without increased urinary albumin excretion. Increased urinary albumin excretion was defined according to the ACR ranges greater or equal than 30 mg/g.

RESULTS

Pearson's correlation analysis and multivariate linear regression analysis revealed that body mass index (BMI), waist circumference and body fat content were significantly correlated with ACR (all P<0.01). Prevalence of low-grade albuminuria and increased urinary albumin excretion gradually increased across the BMI, waist circumference and body fat content quartiles (all P for trend<0.0001). Compared with participants in quartile 1 of BMI, waist circumference and body fat content, participants in quartile 4 had increased prevalence of low-grade albuminuria and increased urinary albumin excretion in logistic regression analysis after adjustment for age, sex, physical activity, fasting plasma glucose, triglycerides, low-density lipoprotein cholesterol and HbA1c (all P<0.05).

CONCLUSION

Obesity measures are associated with urinary albumin excretion in middle-aged and elderly Chinese.

Insulin resistance is associated with all chronic complications in type 1 diabetes

BACKGROUND

Insulin resistance (IR) is present in type 1 diabetes mellitus (T1DM) and is suggested to be related to chronic diabetic complications. The primary aim of our study was to assess IR in T1DM patients with and without chronic complications. A secondary aim was to evaluate the possible association between IR and chronic diabetic complications.

METHODS

This cross-sectional study enrolled 272 patients with T1DM. Insulin resistance was quantified using the estimated glucose disposal rate (eGDR). Associations between eGDR and each diabetes complication were first evaluated using binary logistic regression, then multiparametric logistic regression with stepwise selection of covariates. The discriminative value of eGDR was assessed by receiver operating characteristic (ROC) curve analysis.

RESULTS

Estimated GDR was lower in patients with chronic diabetic complications (6.1 vs. 6.9 mg/kg per min [P = 0.02] for retinopathy; 6.3 vs. 7.3 mg/kg per min [P < 0.01] for nephropathy; 6.5 vs. 7.6 mg/kg per min [P < 0.01] for neuropathy; and 5.2 vs. 7.5 mg/kg per min [P < 0.01] for cardiovascular complications). In univariate analysis eGDR was associated all diabetic complications. These associations remained significant after adjustment for different variables in the final regression models. In addition, eGDR was a good discriminator for each diabetic complication, with an area under the curve between 0.609 and 0.759.

CONCLUSIONS

Patients with chronic diabetic complications are more insulin resistant than those without complications. Moreover, IR was independently associated with the presence of each chronic diabetic complication, and seems to be a good discriminator for them all.

Fatty acid induced metabolic memory involves alterations in renal histone H3K36me2 and H3K27me3

Accumulating evidence suggest that diabetic complications persist even after the maintenance of normal glucose levels. However, the molecular mechanisms involved are still unclear. In the present study, we have investigated the molecular mechanism behind the presence of insulin resistance (IR) condition even after normalization of circulating lipids levels both in vivo and in vitro. Persistent inhibition of insulin signalling in absence of elevated circulating lipids level confirms the presence of metabolic memory in our model of IR. IR in human urine derived podocyte-like epithelial cells (HUPECs) was developed by incubating cells with palmitate (750 μM) for 24 h and in SD rats by feeding high fat diet for 16 weeks. Inhibition of insulin induced FOXO1 (regulator of gluconeogenic genes) degradation persisted even after 48 h of palmitate removal from the culture media. Metabolic memory by palmitate was found to be associated with increased FOXO1 activity as evident from increased expression of FOXO1 target genes such as PDK4, p21, G6Pc and IGFBP1. To understand the reason for prolonged activation of FOXO1 and its target genes, chromatin immuno-precipitation (ChIP) was performed with histone H3K36me2 and H3K27me3 antibodies. ChIP assay shows persistent increase in abundance of histone H3K36me2 on promoter region of FOXO1. We also show decreased abundance of histone H3K27me3 on promoter region of FOXO1, in the kidneys of HFD fed rats, which persisted even after 8 weeks of diet reversal. Taken together, we provide first evidence that circulating lipids generate metabolic memory possibly by altering the abundance of histone H3K36me2 and H3K27me3 on FOXO1 promoter.