Insulin resistance and beta-cell dysfunction in newly diagnosed type 2 diabetes: Expression, aggregation and predominance. Verona Newly Diagnosed Type 2 Diabetes Study 10

AIMS

We investigated quantitative expression, mutual aggregation and relation with hyperglycemia of insulin resistance (IR) and beta-cell dysfunction (BCD) in newly diagnosed type 2 diabetes.

METHODS

We assessed IR with euglycemic hyperinsulinemic clamp and BCD with modelled glucose/C-peptide response to oral glucose in 729 mostly drug-naïve patients. We measured glycated hemoglobin, pre-prandial, post-prandial and meal-related excursion of blood glucose.

RESULTS

IR was found in 87.8% [95% confidence intervals 85.4-90.2] and BCD in 90.0% [87.8-92.2] of subjects, ranging from mild to moderate or severe. Approximately 20% of subjects had solely one defect: BCD 10.8% [8.6-13.1] or IR 8.6% [6.6-10.7]. Insulin resistance and BCD aggregated in most subjects (79.1% [76.2-82.1]). We arbitrarily set nine possible combinations of mild, moderate or severe IR and mild, moderate or severe BCD, finding that each had a similar frequency (∼10%). In multiple regression analyses parameters of glucose control were related more strongly with BCD than with IR.

CONCLUSIONS

In newly-diagnosed type 2 diabetes, IR and BCD are very common with a wide range of expression but no specific pattern of aggregation. Beta-cell dysfunction is likely to play a greater quantitative role than IR in causing/sustaining hyperglycemia in newly-diagnosed type 2 diabetes.

Glomerular filtration rate decline in T2DM following diagnosis. The Verona newly diagnosed diabetes study-12

AIMS

Nephropathy is a complication of type 2 diabetes, with increased albuminuria and reduced glomerular filtration rate (GFR) as biomarkers. Rates of progression to end-stage-renal disease are variable among patients. In this study we have examined the GFR decline in newly diagnosed T2DM.

METHODS

A cohort of 410 patients with newly diagnosed T2DM and with at least four serum creatinine during the follow-up period were recruited. A linear model was used to calculate the decline in eGFR. A multivariable logistic model was used to identify independent predictors of rapid eGFR decline.

RESULTS

Average follow-up was 12.4 years. The eGFR change was -0.80 ± 2.23 ml/min/1.73 m² per year. Patients were arbitrarily stratified into rapid decliners (≤-3.0 ml/min/1.73 m² per year), moderate decliners (-2.9/-1 ml/min/1.73 m² per year) and slow/no decliners (>-1.0 ml/min/1.73 m² per year). Subjects in the 3 categories were 11.4%, 27.3%, and 61.3%, respectively. Albuminuria was the stronger predictor of rapid eGFR decline.

CONCLUSIONS

A rapid decline in eGFR occurs in approximately 1 out of 10 newly diagnosed subjects. This rapid decline can be predicted by widely accessible clinical features, such as albuminuria. Identification of rapid decliners may help to reduce progression toward advanced stages of nephropathy.

Chronic complications in patients with newly diagnosed type 2 diabetes: prevalence and related metabolic and clinical features: the Verona Newly Diagnosed Type 2 Diabetes Study (VNDS) 9

INTRODUCTION

We explored the presence of chronic complications in subjects with newly diagnosed type 2 diabetes referred to the Verona Diabetes Clinic. Metabolic (insulin secretion and sensitivity) and clinical features associated with complications were also investigated.

RESEARCH DESIGN AND METHODS

The comprehensive assessment of microvascular and macrovascular complications included detailed medical history, resting ECG, ultrasonography of carotid and lower limb arteries, quantitative neurological evaluation, cardiovascular autonomic tests, ophthalmoscopy, kidney function tests. Insulin sensitivity and beta-cell function were assessed by state-of-the-art techniques (insulin clamp and mathematical modeling of glucose/C-peptide curves during oral glucose tolerance test).

RESULTS

We examined 806 patients (median age years, two-thirds males), of whom prior clinical cardiovascular disease (CVD) was revealed in 11.2% and preclinical CVD in 7.7%. Somatic neuropathy was found in 21.2% and cardiovascular autonomic neuropathy in 18.6%. Retinopathy was observed in 4.9% (background 4.2%, proliferative 0.7%). Chronic kidney disease (estimated glomerular filtration rate <60 mL/min/1.73 m²) was found in 8.8% and excessive albuminuria in 13.2% (microalbuminuria 11.9%, macroalbuminuria 1.3%).Isolated microvascular disease occurred in 30.8%, isolated macrovascular disease in 9.3%, a combination of both in 9.1%, any complication in 49.2% and no complications in 50.8%.Gender, age, body mass index, smoking, hemoglobin A1c and/or hypertension were independently associated with one or more complications. Insulin resistance and beta-cell dysfunction were associated with macrovascular but not microvascular disease.

CONCLUSIONS

Despite a generally earlier diagnosis for an increased awareness of the disease, as many as ~50% of patients with newly diagnosed type 2 diabetes had clinical or preclinical manifestations of microvascular and/or macrovascular disease. Insulin resistance might play an independent role in macrovascular disease.

TRIAL REGISTRATION NUMBER

NCT01526720.

Metabolic control and complications in Italian people with diabetes treated with continuous subcutaneous insulin infusion

BACKGROUND AND AIM

The objective of this cross-sectional study was to evaluate the degree of glycaemic control and the frequency of diabetic complications in Italian people with diabetes who were treated with continuous subcutaneous insulin infusion (CSII).

METHODS AND RESULTS

Questionnaires investigating the organisation of diabetes care centres, individuals' clinical and metabolic features and pump technology and its management were sent to adult and paediatric diabetes centres that use CSII for treatment in Italy. Information on standard clinical variables, demographic data and acute and chronic diabetic complications was derived from local clinical management systems. The sample consisted of 6623 people with diabetes, which was obtained from 93 centres. Of them, 98.8% had type 1 diabetes mellitus, 57.2% were female, 64% used a conventional insulin pump and 36% used a sensor-augmented insulin pump. The median glycated haemoglobin (HbA_1c) level was 60 mmol/mol (7.6%). The HbA_1c target (i.e. <58 mmol/mol for age <18 years and <53 mmol/mol for age >18 years) was achieved in 43.4% of paediatric and 23% of adult participants. Factors such as advanced pump functions, higher rate of sensor use, pregnancy in the year before the study and longer duration of diabetes were associated with lower HbA_1c levels. The most common chronic complications occurring in diabetes were retinopathy, microalbuminuria and hypertension. In the year before the study, 5% of participants reported ≥1 episode of severe hypoglycaemic (SH) episodes (SH) and 2.6% reported ≥1 episode of ketoacidosis.

CONCLUSIONS

Advanced personal skills and use of sensor-based pump are associated with better metabolic control outcomes in Italian people with diabetes who were treated with CSII. The reduction in SH episodes confirms the positive effect of CSII on hypoglycaemia.

CLINICAL TRIAL REGISTRATION NUMBER

NCT 02620917 (ClinicalTrials.gov).

A Novel Insulin/Glucose Model after a Mixed-Meal Test in Patients with Type 1 Diabetes on Insulin Pump Therapy

Current closed-loop insulin delivery methods stem from sophisticated models of the glucose-insulin (G/I) system, mostly based on complex studies employing glucose tracer technology. We tested the performance of a new minimal model (GLUKINSLOOP 2.0) of the G/I system to characterize the glucose and insulin dynamics during multiple mixed meal tests (MMT) of different sizes in patients with type 1 diabetes (T1D) on insulin pump therapy (continuous subcutaneous insulin infusion, CSII). The GLUKINSLOOP 2.0 identified the G/I system, provided a close fit of the G/I time-courses and showed acceptable reproducibility of the G/I system parameters in repeated studies of identical and double-sized MMTs. This model can provide a fairly good and reproducible description of the G/I system in T1D patients on CSII, and it may be applied to create a bank of “virtual” patients. Our results might be relevant at improving the architecture of upcoming closed-loop CSII systems.

Metabolic Effects of Exercise

Exercise has a powerful action on metabolism, and adaptation of the body to changes induced by exercise is fundamental to be able to provide the energy required for muscle contraction and physiological functions of vital tissues. Depending on the intensity and duration of exercise, different mechanisms are called on to make energy available, and under homeostatic control, this is guaranteed by rapid and coordinated changes in the secretion of several hormones. Molecular mechanisms controlling muscle function and fiber phenotype are related to the specific mode of muscle activation. We can distinguish between two fundamental types of physical activity, endurance exercise and strength exercise, although there is a continuum between these exercise modalities. Besides the acute changes induced by a single exercise session, regular exercise may induce chronic adaptations, improving exercise capacity and affecting energy metabolism. Notably, although acute metabolic effects of exercise are mostly due to insulin-independent effects, exercise training may improve muscle insulin sensitivity and is considered a key tool in the prevention and treatment of metabolic disorders. This chapter focuses on the biochemistry of energy supply to the exercising muscle, on molecular mechanisms involved and on the physiology of energy metabolism during exercise in healthy subjects and patients with insulin resistance and/or diabetes.

Interleukin-6 as a potential positive modulator of human beta-cell function: an exploratory analysis-the Verona Newly Diagnosed Type 2 Diabetes Study (VNDS) 6

AIMS

Recent studies in mouse models of T2D showed that interleukin-6 (IL-6), released from skeletal muscle, is associated with increased glucose-dependent insulin secretion. Few data currently exist exploring the relationship between IL-6 and beta-cell function in humans. We investigated whether IL-6 is positively associated with beta-cell function in newly diagnosed T2D. We extended the same analyses to IL-10, because it regulated similarly to IL-6 in skeletal muscle, and TNF-α and C-reactive protein (CRP), as general biomarkers of inflammation.

METHODS

In 330 VNDS participants, we assessed (1) basal plasma concentrations of IL-6, IL-10, TNF-α, and CRP; (2) beta-cell function, estimated by OGTT minimal modeling and expressed as derivative (DC) and proportional control (PC); (3) insulin sensitivity, by euglycemic insulin clamp.

RESULTS

IL-6 was positively associated with PC in both univariate analysis (p = 0.04) and after adjustment for age, sex, BMI, HbA1c, and M-clamp (p = 0.01). HbA1c was the major independent contributor to the overall variance of PC (16 %), followed by BMI and IL-6 (~2 % each). Similar results were obtained for IL-10 (p = 0.048, univariate; p = 0.04, fully adjusted). TNF-α and CRP were not significantly associated with any component of beta-cell function.

CONCLUSIONS

Our data are the first evidence in human subjects that an endocrine loop involving IL-6 may act as positive modulator of glucose-dependent insulin secretion. Further functional studies are needed to corroborate IL-6 system as a potential druggable target in diabetes.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01526720 ( http://www.clinicaltrial.gov ).

Prevalence of neuropathy in type 2 diabetic patients and its association with other diabetes complications: The Verona Diabetic Foot Screening Program

AIMS

Somatic neuropathy is a chronic complication of diabetes. The purpose of our study was to determine prevalence and clinical variables associated with somatic neuropathy applying a simple screening method.

METHODS

All outpatients with type 2 diabetes attending our diabetic clinic were offered to participate into a diabetic foot screening program, in the period January 2004-December 2012. A total of 3,591 diabetic patients (55.5% men, age 68±10years) underwent detection of somatic neuropathy using the Michigan Neuropathy Screening Instrument in its parts of symptoms (administering a questionnaire) and clinical assessment slightly modified (evaluating foot inspection, vibration sensation by biothesiometer, ankle reflexes).

RESULTS

The prevalence of somatic neuropathy was 2.2% in men and 5.5% in women (p<0.001) when assessed by symptom questionnaire, whereas it was 30.5% in men and 30.8% (p=NS) in women when identified by clinical assessment. In subjects with somatic neuropathy macro- and microvascular complications of diabetes were significantly more common. In multivariate logistic regression analyses BMI, HbA1c and ankle/brachial index independently predicted the presence of neuropathy.

CONCLUSION

The prevalence of somatic neuropathy in type 2 diabetes is nearly 30% when searched with clinical examination. Poor metabolic control, excess body weight and peripheral arteriopathy are independent markers of somatic neuropathy.

Prevalence of Cardiovascular Autonomic Neuropathy in a Cohort of Patients With Newly Diagnosed Type 2 Diabetes: The Verona Newly Diagnosed Type 2 Diabetes Study (VNDS)

OBJECTIVE

Cardiovascular autonomic diabetic neuropathy (CAN) is a serious complication of diabetes. No reliable data on the prevalence of CAN among patients with newly diagnosed type 2 diabetes are available. Therefore, the aim of this study was to estimate the prevalence of CAN among patients with newly diagnosed type 2 diabetes.

RESEARCH DESIGN AND METHODS

A cohort of 557 patients with newly diagnosed type 2 diabetes with cardiovascular autonomic test results available was selected. Early and confirmed neuropathy were assessed using a standardized methodology and their prevalences determined. A multivariate logistic regression analysis was modeled to study the factors associated with CAN.

RESULTS

In the entire cohort, the prevalence of confirmed CAN was 1.8%, whereas that of early CAN was 15.3%. Prevalence did not differ between men and women. In the multivariate analyses BMI results were independently and significantly associated with CAN after adjusting for age, sex, hemoglobin A1c, pulse pressure, triglyceride-to-HDL cholesterol ratio, kidney function parameters, and antihypertensive treatment.

CONCLUSIONS

CAN could be detected very early in type 2 diabetes. This study may suggest the importance of performing standardized cardiovascular autonomic tests after diagnosis of type 2 diabetes.

Lower levels of 25-hydroxyvitamin D3 are associated with a higher prevalence of microvascular complications in patients with type 2 diabetes

OBJECTIVE

Low levels of serum 25-hydroxyvitamin D [25(OH)D] are commonly found in type 2 diabetes. We examined whether there is an association between circulating 25(OH)D concentrations and the presence of microvascular complications in people with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We studied 715 outpatients with type 2 diabetes who regularly attended our clinic. Participants were evaluated for the presence of microvascular complications (namely retinopathy and/or nephropathy) by clinical evaluation, fundus examination, urine examination and biochemical tests. Serum 25(OH)D levels were also measured for each participant.

RESULTS

Hypovitaminosis D (ie, a serum 25(OH)D level <30 ng/mL) was found in 75.4%, while deficiency (ie, a 25(OH)D level <20 ng/mL) was found in 36.6% of these patients. Serum 25(OH)D levels decreased significantly in relation to the severity of either retinopathy or nephropathy or both. In multivariate logistic regression analysis, lower 25(OH)D levels were independently associated with the presence of microvascular complications (considered as a composite end point; OR 0.758; 95% CI 0.607 to 0.947, p=0.015). Notably, this association remained significant even after excluding those with an estimated glomerular filtration rate <60 mL/min/1.73 m(2).

CONCLUSIONS

We found an inverse and independent relationship between circulating 25(OH)D levels and the prevalence of microvascular complications in patients with type 2 diabetes. However, vitamin D may be simply a marker and causality cannot be implied from our cross-sectional study. Whether vitamin D supplementation in patients with type 2 diabetes may have beneficial effects on the risk of microvascular complications remains to be investigated.

Glycated haemoglobin is inversely related to serum vitamin D levels in type 2 diabetic patients

Objective

A correlation between glucose control and 25(OH)D metabolism has been suggested by previous studies. However, this correlation has not yet been evaluated considering the impact of chronic complications of type 2 diabetes, especially the presence of nephropathy. Thus, the aim of this study was to determine the correlation between A1C and 25(OH)D in a well characterized cohort of type 2 diabetic patients.

Research Design and Methods

We cross-sectionally examined the association between A1C and serum 25(OH) D in 715 type 2 diabetic patients attending our clinic during the years 2011–2012. The average age was 68±12 years (range 26–94 years). The relation between A1C and serum 25(OH)D levels was modelled by multiple linear regression analyses.

Results

Serum 25(OH)D levels were inversely associated with A1C levels (r = −0.116, p = .003). This relation maintains its independence in the multivariate analysis after adjusting for age, sex, A1C, BMI, treatment and duration of diabetes and nephropathy.

Conclusions

In type 2 diabetic patients, high A1C levels are associated with low concentrations of serum 25(OH)D independently of duration of diabetes, diabetic treatment and nephropathy. Future studies are needed to clarify the biological relation between glucose control and vitamin D metabolism in type 2 diabetes.

[Abdominal obesity and diabetes]

It has been known for about 50 years that different obesity phenotypes do exist. Nonetheless, how abdominal, namely visceral, obesity is burdened by metabolic and cardiovascular diseases has been established only in recent years. The association between abdominal obesity and diabetes, which is well documented, has been mainly explained by the lower insulin sensitivity of subjects with excess visceral fat. However, more recent studies support the hypothesis that several molecules released in greater or lower amount by visceral adipocytes can exert also a detrimental role on beta-cell function. Among these molecules free fatty acids and adipokines should be mentioned. The latter include inflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-6 and hormones synthesized by adipocytes, such as adiponectin, leptin and resistin. Visceral obesity is also associated with an excessive depot of triglycerides and other lipid products (e.g., ceramide) within the key organs of glucose metabolism (liver, skeletal muscle, pancreatic islets). This phenomenon seems to contribute to both insulin resistance and beta-cell dysfunction, favoring abnormalities of glucose homeostasis.