Insulin resistance is a poor predictor of type 2 diabetes in individuals with no family history of disease

Rising tide: The global surge of type 2 diabetes in children and adolescents demands action now

Childhood-onset obesity has emerged as a major public healthcare challenge across the globe, fueled by an obesogenic environment and influenced by both genetic and epigenetic predispositions. This has led to an exponential rise in the incidence of type 2 diabetes mellitus in children and adolescents. The looming wave of diabetes-related complications in early adulthood is anticipated to strain the healthcare budgets in most countries. Unless there is a collective global effort to curb the devastation caused by the situation, the impact is poised to be pro-found. A multifaceted research effort, governmental legislation, and effective social action are crucial in attaining this goal. This article delves into the current epidemiological landscape, explores evidence concerning potential risks and consequences, delves into the pathobiology of childhood obesity, and discusses the latest evidence-based management strategies for diabesity.

A novel simple disposition index (SPINA-DI) from fasting insulin and glucose concentration as a robust measure of carbohydrate homeostasis

AIMS

The widely used dynamic disposition index, derived from oral glucose tolerance testing, is an integrative measure of the homeostatic performance of the insulin-glucose feedback control. Its collection is, however, time consuming and expensive. We, therefore, pursued the question if such a measure can be calculated at baseline/fasting conditions using plasma concentrations of insulin and glucose.

METHODS

A new fasting-based disposition index (structure parameter inference approach-disposition index [SPINA-DI]) was calculated as the product of the reconstructed insulin receptor gain (SPINA-GR) times the secretory capacity of pancreatic beta cells (SPINA-GBeta). The novel index was evaluated in computer simulations and in three independent, multiethnic cohorts. The objectives were distribution in various populations, diagnostic performance, reliability and correlation to established physiological biomarkers of carbohydrate metabolism.

RESULTS

Mathematical and in-silico analysis demonstrated SPINA-DI to mirror the hyperbolic relationship between insulin sensitivity and beta-cell function and to represent an optimum of the homeostatic control. It significantly correlates to the oral glucose tolerance test based disposition index and other important physiological parameters. Furthermore, it revealed higher discriminatory power for the diagnosis of (pre)diabetes and superior retest reliability than other static and dynamic function tests of glucose homeostasis.

CONCLUSIONS

SPINA-DI is a novel simple reliable and inexpensive marker of insulin-glucose homeostasis suitable for screening purposes and a wider clinical application.

Moderate-intensity endurance training improves late phase β-cell function in adults with type 2 diabetes

Physical activity is important for type 2 diabetes treatment, yet the underlying mechanisms for these beneficial effects of exercise are not fully understood. Here, we investigated the effects of exercise training on biphasic β-cell insulin secretory function, a key factor regulating blood glucose. Adults with type 2 diabetes (7F/3M, age 49 ± 5 years, BMI 30 ± 3 kg/m²) completed a 10-week moderate-intensity exercise program and multiple components of glucose homeostasis were measured. Training improved glycemic control, insulin sensitivity, and processing of proinsulin-to-insulin. Training increased late phase β-cell function by 38% (p = 0.01), which was correlated with changes in VO_2peak suggesting training response-dependent effects. Ras-Responsive Element Binding Protein 1 (RREB1) concentrations, a protein postulated to increase type 2 diabetes risk, were inversely correlated with increases in training-induced late-phase disposition index, consistent with an inhibitory role of RREB1 on insulin secretion. Moderate-intensity exercise training improves late-phase β-cell function and glycemic control in adults with type 2 diabetes.

Insulin-resistance in paediatric age: Its magnitude and implications

Insulin resistance (IR) is insulin failure in normal plasma levels to adequately stimulate glucose uptake by the peripheral tissues. IR is becoming more common in children and adolescents than before. There is a strong association between obesity in children and adolescents, IR, and the metabolic syndrome components. IR shows marked variation among different races, crucial to understanding the possible cardiovascular risk, specifically in high-risk races or ethnic groups. Genetic causes of IR include insulin receptor mutations, mutations that stimulate autoantibody production against insulin receptors, or mutations that induce the formation of abnormal glucose transporter 4 molecules or plasma cell membrane glycoprotein-1 molecules; all induce abnormal energy pathways and end with the development of IR. The parallel increase of IR syndrome with the dramatic increase in the rate of obesity among children in the last few decades indicates the importance of environmental factors in increasing the rate of IR. Most patients with IR do not develop diabetes mellitus (DM) type-II. However, IR is a crucial risk factor to develop DM type-II in children. Diagnostic standards for IR in children are not yet established due to various causes. Direct measures of insulin sensitivity include the hyperinsulinemia euglycemic glucose clamp and the insulin-suppression test. Minimal model analysis of frequently sampled intravenous glucose tolerance test and oral glucose tolerance test provide an indirect estimate of metabolic insulin sensitivity/resistance. The main aim of the treatment of IR in children is to prevent the progression of compensated IR to decompensated IR, enhance insulin sensitivity, and treat possible complications. There are three main lines for treatment: Lifestyle and behavior modification, pharmacotherapy, and surgery. This review will discuss the magnitude, implications, diagnosis, and treatment of IR in children.

Prevalence of metabolic syndrome and predictors of metabolic risk in Indian children, adolescents and youth with type 1 diabetes mellitus

INTRODUCTION

Children with type 1 diabetes (T1D) are at the same risk of developing metabolic syndrome (MS) as the general population. Several environmental factors such as lifestyle, exogenous insulin therapy (over-insulinization) and genetic/familial factors are thought to underlie the phenotype of 'double diabetes' (co-existence of MS components in patients with T1D).

OBJECTIVES

To determine the prevalence of overweight/obesity and MS and to identify its predictors in Indian children, adolescents and young adults with T1D.

METHODS

This cross-sectional study included 355 children and youth aged 6-23 years with T1D. Demographic data were obtained from patients using questionnaires. Anthropometry, blood pressure, sexual maturity rating, biochemical measurements and body composition measurements were performed using standard protocols. Insulin resistance (IR) was calculated using estimated glucose disposal rate (eGDR) and MS was diagnosed using the international diabetes federation (IDF) consensus definition 2017.

RESULTS

The prevalence of overweight/obesity and MS in our study was 15.5% and 4.5%, respectively. Abnormal HDL-cholesterol was the most common component of MS (55.6%) among children with T1D. Age, gender, body mass index (BMI) and eGDR were identified as significant predictors of the likelihood of MS.

CONCLUSIONS

We found a similar prevalence of MS in children with T1D as compared to other healthy children, which emphasises the need for monitoring of eGDR to determine IR in these children.

Signaling defects associated with insulin resistance in nondiabetic and diabetic individuals and modification by sex

Insulin resistance is present in one-quarter of the general population, predisposing these people to a wide range of diseases. Our aim was to identify cell-intrinsic determinants of insulin resistance in this population using induced pluripotent stem cell-derived (iPSC-derived) myoblasts (iMyos). We found that these cells exhibited a large network of altered protein phosphorylation in vitro. Integrating these data with data from type 2 diabetic iMyos revealed critical sites of conserved altered phosphorylation in IRS-1, AKT, mTOR, and TBC1D1 in addition to changes in protein phosphorylation involved in Rho/Rac signaling, chromatin organization, and RNA processing. There were also striking differences in the phosphoproteome in cells from men versus women. These sex-specific and insulin-resistance defects were linked to functional differences in downstream actions. Thus, there are cell-autonomous signaling alterations associated with insulin resistance within the general population and important differences between men and women, many of which also occur in diabetes, that contribute to differences in physiology and disease.

100 years of insulin: celebrating the past, present and future of diabetes therapy

The year 2021 marks the centennial of Banting and Best's landmark description of the discovery of insulin. This discovery and insulin's rapid clinical deployment effectively transformed type 1 diabetes from a fatal diagnosis into a medically manageable chronic condition. In this Review, we describe key accomplishments leading to and building on this momentous occasion in medical history, including advancements in our understanding of the role of insulin in diabetes pathophysiology, the molecular characterization of insulin and the clinical use of insulin. Achievements are also viewed through the lens of patients impacted by insulin therapy and the evolution of insulin pharmacokinetics and delivery over the past 100 years. Finally, we reflect on the future of insulin therapy and diabetes treatment, as well as challenges to be addressed moving forward, so that the full potential of this transformative discovery may be realized.

Reversing the tide - diagnosis and prevention of T2DM in populations of African descent

Populations of African descent are at the forefront of the worldwide epidemic of type 2 diabetes mellitus (T2DM). The burden of T2DM is amplified by diagnosis after preventable complications of the disease have occurred. Earlier detection would result in a reduction in undiagnosed T2DM, more accurate statistics, more informed resource allocation and better health. An underappreciated factor contributing to undiagnosed T2DM in populations of African descent is that screening tests for hyperglycaemia, specifically, fasting plasma glucose and HbA_1c, perform sub-optimally in these populations. To offset this problem, combining tests or adding glycated albumin (a nonfasting marker of glycaemia), might be the way forward. However, differences in diet, exercise, BMI, environment, gene-environment interactions and the prevalence of sickle cell trait mean that neither diagnostic tests nor interventions will be uniformly effective in individuals of African, Caribbean or African-American descent. Among these three populations of African descent, intensive lifestyle interventions have been reported in only the African-American population, in which they have been found to provide effective primary prevention of T2DM but not secondary prevention. Owing to a lack of health literacy and poor glycaemic control in Africa and the Caribbean, customized lifestyle interventions might achieve both secondary and primary prevention. Overall, diagnosis and prevention of T2DM requires innovative strategies that are sensitive to the diversity that exists within populations of African descent.

Ethnic differences in glucose effectiveness and disposition index in overweight/obese African American and white women with prediabetes: A study of compensatory mechanisms

OBJECTIVE

Prediabetes, a major precursor of type 2 diabetes, varies among ethnic populations. Therefore, we compared the pathophysiologic mechanisms of prediabetes in overweight/obese African American (AA) and White American (WA) women.

SUBJECTS AND METHODS

We recruited 95 women (67 AA, 28 WA) with prediabetes. Standard OGTT and FSIVGTT were performed in each subject. Insulin sensitivity (Si), glucose effectiveness (Sg), beta cell function (acute insulin response to glucose (AIRg) and disposition index (DI: Si×AIRg) were calculated using Bergman's Minmod.

RESULTS

Mean BMI was greater in AA vs WA with prediabetes (38.3±8.2vs 34.6±8.5kg/m², p=0.05). Mean fasting serum glucose, and insulin levels were lower in AA vs WA. Similarly, mean peak serum glucose levels were lower while peak insulin levels were higher at 30 and 60minutes in AA vs WA. In contrast, mean fasting and peak serum c-peptide levels at 60 and 90minutes were significantly lower in AA vs WA. Mean AIRg was higher but not significantly different in AA vs WA (633±520.92 vs 414.8±246.8, p=0.193). Although, Si (2.93±3.25vs 44 2.50±1.76 (×10^-4×min^-1 [μU/ml]^-1), p=0.448) was not different, DI was significantly higher in AA vs WA (1381±1126 vs 901.9±477.1, p=0.01). In addition, mean Sg was significantly higher in AAvs WA (2.51±1.17 vs 1.97±0.723 (×10^-2/min), p=0.02).

CONCLUSIONS

We found that in overweight/obese prediabetic AA and WA women with similar Si, the mean Sg and DI were significantly higher in AA. We conclude that the pathophysiologic mechanisms of prediabetes differ in the overweight/obese AA and WA women.

Molecular mechanisms redirecting the GLP-1 receptor signalling profile in pancreatic β-cells during type 2 diabetes

Treatments with β-cell preserving properties are essential for the management of type 2 diabetes (T2D), and the new therapeutic avenues, developed over the last years, rely on the physiological role of glucagon-like peptide-1 (GLP-1). Sustained pharmacological levels of GLP-1 are achieved by subcutaneous administration of GLP-1 analogues, while transient and lower physiological levels of GLP-1 are attained following treatment with inhibitors of dipeptidylpeptidase 4 (DPP4), an endoprotease which degrades the peptide. Both therapeutic classes display a sustained and durable hypoglycaemic action in patients with T2D. However, the GLP-1 incretin effect is known to be reduced in patients with T2D, and GLP-1 analogues and DPP4 inhibitors were shown to lose their effectiveness over time in some patients. The pathological mechanisms behind these observations can be either a decrease in GLP-1 secretion from intestinal L-cells and, as a consequence, a reduction in GLP-1 plasma concentrations, combined or not with a reduced action of GLP-1 in the β-cell, the so-called GLP-1 resistance. Much evidence for a GLP-1 resistance of the β-cell in subjects with T2D have emerged. Here, we review the potential roles of the genetic background, the hyperglycaemia, the hyperlipidaemia, the prostaglandin E receptor 3, the nuclear glucocorticoid receptor, the GLP-1R desensitization and internalisation processes, and the β-arrestin-1 expression levels on GLP-1 resistance in β-cells during T2D.

Insulin resistance of protein anabolism accompanies that of glucose metabolism in lean, glucose-tolerant offspring of persons with type 2 diabetes

OBJECTIVE

To test whether protein anabolic resistance is an early defect in type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

Seven lean, normoglycemic T2D offspring (T2D-O) and eight matched participants without family history (controls; C) underwent a 3-hour hyperinsulinemic (40 mU/m²/min), euglycemic (5.5 mmol/L) and isoaminoacidemic clamp. Whole-body glucose and protein kinetics were measured with d-[3-³H]glucose and l-[l-¹³C]leucine, respectively. Plasma amino acids were measured by liquid chromatography-tandem mass spectrometry.

RESULTS

Fasting glycemia and glucose kinetic variables did not differ between groups. Clamp decreases in glucose rate of appearance were not different, but rate of disappearance increased 29% less in T2D-O, to a significantly lower rate. Fasting leucine was higher in T2D-O, but kinetics did not differ. Clamp increases in leucine oxidation and decreases in endogenous rate of appearance (protein breakdown) were equal, but in T2D-O, non-oxidative rate of disappearance (protein synthesis) did not increase and net balance (synthesis-breakdown) did not become positive as in C.

CONCLUSIONS

Resistance of whole-body protein anabolism (synthesis and net balance) accompanies resistance of glucose uptake in T2D-O. Mechanisms responsible, possible roles in the increased risk of developing diabetes, and its potential impact on long-term protein balance require definition.

The changing face of diabetes in youth: lessons learned from studies of type 2 diabetes

The incidence of youth type 2 diabetes (T2D), linked with obesity and declining physical activity in high-risk populations, is increasing. Recent multicenter studies have led to a number of advances in our understanding of the epidemiology, pathophysiology, diagnosis, treatment, and complications of this disease. As in adult T2D, youth T2D is associated with insulin resistance, together with progressive deterioration in β cell function and relative insulin deficiency in the absence of diabetes-related immune markers. In contrast to adult T2D, the decline in β cell function in youth T2D is three- to fourfold faster, and therapeutic failure rates are significantly higher in youth than in adults. Whether the more aggressive nature of youth T2D is driven by genetic heterogeneity or physiology/metabolic maladaptation is yet unknown. Besides metformin, the lack of approved pharmacotherapeutic agents for youth T2D that target the pathophysiological mechanisms is a major barrier to optimal diabetes management. There is a significant need for effective therapeutic options, in addition to increased prevention, to halt the projected fourfold increase in youth T2D by 2050 and the consequences of heightened diabetes-related morbidity and mortality at younger ages.

Insulin resistance and its correlation with risk factors for developing diabetes mellitus in 100 omani medical students

OBJECTIVES

The aim of this study was to assess the prevalence of insulin resistance (IR) in healthy young Omanis and relate this with their body mass index (BMI) and family history (FH) of diabetes mellitus (DM).

METHODS

This study was conducted between May 2009 and February 2010 at Sultan Qaboos University, Muscat, Oman. A detailed questionnaire was completed by 50 male and 50 female medical students between 20-25 years old. Fasting blood samples were obtained for serum glucose and insulin measurements. IR was calculated using the homeostasis model assessment-estimated insulin resistance (HOMA-IR) formula (fasting insulin x fasting glucose/22.5) and a value above 2.5 was considered elevated. The results were analysed using the Statistical Package for the Social Sciences (SPSS).

RESULTS

PARTICIPANTS WERE CLASSIFIED INTO THE FOLLOWING BMI CATEGORIES: 59% were normal (18.5-24.9 kg/m(2)), 26% were overweight or obese (>24.9 kg/m(2)) and 15% were underweight (<18.5 kg/m(2)). A FH of DM was present in 74%. The HOMA-IR index was elevated in 16% and was directly correlated to the BMI (P = 0.003). There was no correlation between IR and a positive FH of DM.

CONCLUSION

There is a high prevalence of IR (16%) and obesity (26%) in healthy young Omani medical students. Counselling is recommended for all overweight and obese individuals in an attempt to prevent or delay the onset of DM in the future.

Longitudinal changes in insulin sensitivity, insulin secretion, beta cell function and glucose effectiveness during development of non-diabetic hyperglycemia in a Japanese population

Since there had been no previous studies of alterations in insulin sensitivity, glucose-stimulated insulin secretion, beta cell function and glucose effectiveness during the development of non-diabetic hyperglycemia in Asian populations, we conducted a longitudinal study of such changes in 244 Japanese adults with normal glucose tolerance (median BMI 23.3 kg/m² and age 51 yrs). The median follow-up period was 3.3 yrs. One hundred and eighty-two subjects maintained normal glucose tolerance (nonprogressors). After excluding the 3 subjects who progressed to diabetes, we analyzed the 59 who developed non-diabetic hyperglycemia (progressors), of which 31 progressed to impaired fasting glucose and 28 to impaired glucose tolerance. Whole body insulin sensitivity was estimated by ISI_Matsuda, glucose-stimulated insulin secretion by [δIRI_0-30/δPG_0-30] and Stumvoll indices, hepatic insulin sensitivity by quantitative insulin sensitivity check index (QUICKI) and 1/fasting IRI, beta cell function by oral disposition index (DI_O) ([δIRI_0-30/δPG_0-30]∙[ISI_Matsuda]), and glucose effectiveness by an OGTT-derived index (SgI_O). ISI_Matsuda (p <0.05), [δIRI_0-30/δPG_0-30], DI_O and SgI_O (both p <0.01), but not QUICKI, 1/fasting IRI, or Stumvoll-1st and -2nd phases, were lower in the progressors at baseline. This group was also characterized by the following: 1) ISI_Matsuda, DI_O and SgI_O were reduced by 34%, 32% and 11%, respectively (all p <0.01); 2) QUICKI and 1/fasting IRI diminished by 21% and 5%, respectively (both p <0.01); and 3) no significant changes were found in [δIRI_0-30/δPG_0-30], Stumvoll-1st and -2nd phases or BMI during the follow-up. In the nonprogressors, no indices changed significantly during the follow-up. Our study concluded that during the transition from normal glucose tolerance to non-diabetic hyperglycemia in this non-obese population, whole body insulin sensitivity, hepatic insulin sensitivity, beta cell function, and glucose effectiveness were all attenuated, but no significant changes in glucose-stimulated insulin secretion occurred. Also of note is the fact that the transition took place without any accompanying increase in BMI.

Early decrease of insulin sensitivity in offspring of individuals with type 2 diabetes. The Mexican Diabetes Prevention Study

BACKGROUND AND AIMS

Defects in insulin sensitivity (IS) and insulin secretion have been recognized as risk factors for type 2 diabetes (T2D) and its complications. We undertook this study to establish the relationship between healthy type 2 diabetic offspring (OFD) from a Mexican population with IS.

METHODS

A total of 602 Mexican subjects, 359 first-degree offspring of T2D (OFD+) and 243 first-degree non-offspring of T2D (OFD-) were classified as young adults (age range, 18-44 years) and middle-aged adults (age range, 45-65 years). Groups were clinically and biochemically characterized. Quantitative insulin sensitivity check index (QUICKI) was used to estimate IS and the homeostasis model assessment B (HOMA-B) was used to estimate B cell function.

RESULTS

IS decreased significantly (p <0.05) in OFD+ middle-aged (QUICKI 0.330 ± 0.03) compared with OFD- (0. 370 ± 0.03). Middle-aged adults (OFD+) had the highest prevalence of increased fasting insulin levels (FIL) (13.6%) and decreased IS (22.9%) compared with OFD- groups (3.2%). A binary regression analysis showed the association of OFD+ with increased FIL (odds ratio [OR], 3.71; 95% confidence interval [95% CI], 1.68-8.2; p = 0.001), and QUICKI (OR, 10.87; 95% CI, 2.36-44.69; p <0.01) adjusted by gender, age, and obesity.

CONCLUSIONS

Our results suggest that decreased IS itself could be recognized as one of the earliest detectable abnormalities in middle-aged adults. Moreover, prevalence increases with age and is associated with type 2 diabetic offspring, regardless of obesity.

The evolution of non-diabetic hyperglycemia: a longitudinal study

The risk factors for impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) have yet to be established. Our aim was to elucidate the predisposing factors for IFG and IGT in Japanese subjects with normal glucose tolerance (NGT). Using a 75 g oral glucose tolerance test (OGTT), we analyzed 604 adults with the ADA-defined NGT. Follow-up glucose tolerance status was determined by 75 g OGTT performed 3.7 yrs later. Glucose-stimulated insulin secretion (GSIS), whole body insulin sensitivity (SI) and beta cell function (BCF) were estimated by Stumvoll indices, ISI(Matsuda), and a product of Stumvoll 1(st) and ISI(Matsuda), respectively, and hepatic SI by quantitative insulin sensitivity check index. Logistic regression analysis revealed that attenuated BCF due to low GSIS was an independent risk factor for IFG. Low whole body SI was an additional risk for IGT. Male gender and high BMI were independently related to the progression to both IFG and IGT, whereas a positive diabetes family history was independently related to IGT. The worsening of glucose tolerance at large was predicted with 66% sensitivity by risk engine with GSIS, whole body SI, gender, BMI and glucose. This finding may help when implementing early intervention strategies for diabetes.

PKCδ is activated in the liver of obese Zucker rats and mediates diet-induced whole body insulin resistance and hepatocyte cellular insulin resistance

Insulin resistance can arise when pathological levels of free fatty acids (FFAs) and proinflammatory cytokines disrupt insulin signaling. Protein kinase C delta (PKCδ) is a FFA- and a proinflammatory cytokine-regulated protein kinase that is associated with inhibition of insulin signaling and action. To gain insight into the role of PKCδ in insulin resistance, PKCδ activation was studied in a genetic model of obesity-linked insulin resistance. PKCδ was found to be activated in the liver of obese insulin-resistant Zucker rats and in isolated cultured hepatocytes. PKCδ was further studied in PKCδ-null mice and their wild-type littermates fed a high-fat or control diet for 10 weeks. PKCδ-null mice on a high-fat diet had improved insulin sensitivity and hepatic insulin signaling compared to wild-type littermates. Additionally, the deleterious effect of a high-fat diet on glucose tolerance in wild-type mice was completely blocked in PKCδ-null mice. To directly test the role of PKCδ in cellular insulin resistance, primary hepatocytes from the high-fat diet mice were isolated and stimulated with insulin. Primary hepatocytes from PKCδ-null mice had improved insulin-stimulated Akt and FOXO phosphorylation compared to hepatocytes from wild-type littermates. Consistent with this result, tumor necrosis factor alpha-mediated inhibition of insulin signaling was blocked in PKCδ knockdown primary hepatocytes. These results indicate that PKCδ plays a role in insulin resistance and is consistent with the hypothesis that PKCδ is a negative regulator of insulin signaling and thus may be a therapeutic target for the treatment of type 2 diabetes.

Genetic epidemiology of type 2 diabetes and cardiovascular diseases in Africa

The burdens of type 2 diabetes (T2D) and cardiovascular diseases (CVD) are increasing in Africa. T2D and CVD are the result of the complex interaction between inherited characteristics, lifestyle, and environmental factors. The epidemic of obesity is largely behind the exploding global incidence of T2D. However, not all obese individuals develop diabetes and positive family history is a powerful risk factor for diabetes and CVD. Recent implementations of high throughput genotyping and sequencing approaches have advanced our understanding of the genetic basis of diabetes and CVD by identifying several genomic loci that were not previously linked to the pathobiology of these diseases. However, African populations have not been adequately represented in these global genomic efforts. Here, we summarize the state of knowledge of the genetic epidemiology of T2D and CVD in Africa and highlight new genomic initiatives that promise to inform disease etiology, public health and clinical medicine in Africa.

Impact of impaired insulin secretion and insulin resistance on the incidence of type 2 diabetes mellitus in a Japanese population: the Saku study

AIMS/HYPOTHESIS

To assess the impact of impaired insulin secretion (IIS) and insulin resistance (IR) on type 2 diabetes incidence in a Japanese population.

METHODS

This 4 year cohort study included 3,059 participants aged 30-69 without diabetes at baseline who underwent comprehensive medical check-ups between April 2006 and March 2007 at Saku Central Hospital. Based on their insulinogenic index and HOMA-IR values, participants were classified by the criteria of the Japan Diabetes Society into four categories: normal; isolated IIS (i-IIS); isolated IR (i-IR); and IIS plus IR. They were followed up until March 2011. The incidence of type 2 diabetes was determined from fasting and 2 h post-load plasma glucose concentrations and from receiving medical treatment for diabetes.

RESULTS

At baseline, 1,550 individuals (50.7%) were classified as normal, 900 (29.4%) i-IIS, 505 (16.5%) i-IR, and 104 (3.4%) IIS plus IR. During 10,553 person-years of follow-up, 219 individuals developed type 2 diabetes, with 126 (57.5%) having i-IIS at baseline. Relative to the normal group, the multivariable-adjusted HRs for type 2 diabetes in the i-IIS, i-IR and IIS plus IR groups were 8.27 (95% CI 5.33, 12.83), 4.90 (95% CI 2.94, 8.17) and 16.93 (95% CI 9.80, 29.25), respectively. The population-attributable fractions of type 2 diabetes onset due to i-IIS, i-IR, and IIS plus IR were 50.6% (95% CI 46.7%, 53.0%), 14.2% (95% CI 11.8%, 15.6%) and 12.9% (95% CI 12.3%, 13.2%), respectively.

CONCLUSIONS/INTERPRETATION

Compared with IR, IIS had a greater impact on the incidence of type 2 diabetes in a Japanese population.

Effects of endogenous androgens and abdominal fat distribution on the interrelationship between insulin and non-insulin-mediated glucose uptake in females

BACKGROUND

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism and insulin resistance. Glucose disposal occurs via noninsulin-mediated glucose uptake (NIMGU) and insulin-mediated glucose uptake (IMGU). It is unknown whether in PCOS NIMGU increases to compensate for declining IMGU and whether androgens and fat distribution influence this relationship.

OBJECTIVES

The objective of the study was to compare in women with PCOS and controls the interrelationship between NIMGU [ie, glucose effectiveness (Sg)] and IMGU [ie, the insulin sensitivity index (Si)] and the role of androgens and fat distribution.

PARTICIPANTS

Twenty-eight PCOS (by National Institutes of Health 1990 criteria) and 28 control (age, race, and body mass index matched) women were prospectively studied. A subset of 16 PCOS subjects and 16 matched controls also underwent abdominal computed tomography.

MAIN OUTCOME MEASURES

Glucose disposal (by a frequently sampled iv glucose tolerance test), circulating androgens, and abdominal fat distribution [by waist to hip ratio and visceral (VAT) and sc (SAT) adipose tissue content] were measured.

RESULTS

PCOS women had lower mean Si and similar Sg and abdominal fat distribution compared with controls. PCOS women with Si below the PCOS median (more insulin resistant) had a lower mean Sg than controls with Si above the control median (more insulin sensitive). In PCOS only, body mass index, free T, modified Ferriman-Gallwey score, and waist to hip ratio independently predicted Sg, whereas Si did not. In PCOS, VAT and SAT independently and negatively predicted Si and Sg, respectively.

CONCLUSION

The decreased IMGU in PCOS is not accompanied by a compensatory increase in NIMGU or associated with excessive VAT accumulation. Increased general obesity, SAT, and hyperandrogenism are primary predictors of the deterioration of NIMGU in PCOS.

Metabolic effects of adjunctive aripiprazole in clozapine-treated patients with schizophrenia

OBJECTIVE

This study examined the effects of adjunctive aripiprazole therapy on metabolism in clozapine-treated patients with schizophrenia.

METHOD

In an 8-week randomized, double-blind, placebo-controlled study, subjects received either aripiprazole (15 mg/day) or placebo. At baseline and week 8, metabolic parameters were assessed by the frequently sampled intravenous glucose tolerance test, nuclear magnetic resonance spectroscopy and whole-body dual-energy X-ray absorptiometry (DXA).

RESULTS

Thirty subjects completed the study (16 in the aripiprazole group and 14 in the placebo group). Glucose effectiveness measured by the frequently sampled intravenous glucose tolerance test improved significantly in the aripiprazole group (0.003 ± 0.006 vs. -0.005 ± 0.007/min, P = 0.010). The aripiprazole group showed significant reductions in both plasma low-density lipoprotein (LDL) levels (-15.1 ± 19.8 vs. 4.4 ± 22.5 mg/dl, P = 0.019) and LDL particle numbers (-376 ± 632 vs. -36 ± 301 nm, P = 0.035). Further, there was a significant reduction in the lean mass (-1125 ± 1620 vs. 607 ± 1578 g, P = 0.011) measured by whole-body DXA scan in the aripiprazole group. All values were expressed as mean ± standard deviation, aripiprazole vs. placebo.

CONCLUSION

Adjunctive therapy with aripiprazole may have some metabolic benefits in clozapine-treated patients with schizophrenia.

Parental and offspring associations of the metabolic syndrome in the Fels Longitudinal Study

BACKGROUND

Evidence shows that some causes of the metabolic syndrome (MS) begin in childhood, which could indicate a familial association, through either genetic inheritance or cohabitation.

OBJECTIVE

This study examined associations between parents and adult offspring diagnoses of the MS and its risk factors.

DESIGN

Measurements were obtained from adult participants and their adult offspring enrolled in the Fels Longitudinal Study, with simultaneous waist circumference, systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides, HDL, and glucose observations used for diagnosis. On the basis of repeated measurements (in some cases), adult participants were classified as having the MS at least once or as never having the MS. Chi-square tests, ORs, and mixed-effects models were used to study familial associations.

RESULTS

Maternal (OR: 2.5; 95% CI: 1.1, 5.5) and paternal (OR: 4.1; 95% CI: 1.4, 12.1) MS classifications were significantly associated with MS classification in sons. MS classification in mothers and daughters (OR: 2.7; 95% CI: 0.9, 8.7; P = 0.08) was similar to that in sons but was not significant, whereas fathers and daughters were not associated (OR: 1.1; 95% CI: 0.4, 3.5). Maternal MS diagnoses were significantly and positively associated with triglycerides in male offspring and were significantly associated with SBP, DBP, and triglycerides in females. Paternal diagnoses were significantly associated only with DBP and HDL in male offspring.

CONCLUSIONS

Parental MS diagnosis is significantly associated with MS diagnosis in adult male offspring, and adverse levels of certain risk factors are associated between offspring and parents, although these associations vary across risk factors and child sex.

Type 2 diabetes in Asians: prevalence, risk factors, and effectiveness of behavioral intervention at individual and population levels

This review summarizes the current data on diabetes risk factors, prevalence, and prevention efforts in Asia and Asian migrant populations. Studies indicate that type 2 diabetes mellitus is a large and growing threat to public health in Asian populations. Furthermore, Asian subgroups (e.g., South Asians/Asian Indians, Chinese) have unique risk factor profiles for developing diabetes, which differ from other populations and between Asian ethnic groups. Lifestyle intervention programs are effective in preventing diabetes in Asians, as with other ethnicities. The strength of these findings is lessened by the lack of systematically collected data using objective measurements. Large epidemiologic studies of diabetes prevalence and risk factor profiles and translational trials identifying sustainable and culturally acceptable lifestyle programs for Asian subgroups are needed.

Simultaneous measurement of insulin sensitivity, insulin secretion, and the disposition index in conscious unhandled mice

Of the parameters that determine glucose disposal and progression to diabetes in humans: first-phase insulin secretion, glucose effectiveness (Sg), insulin sensitivity (Si), and the disposition index (DI), only Si can be reliably measured in conscious mice. To determine the importance of the other parameters in murine glucose homeostasis in lean and obese states, we developed the frequently sampled intravenous glucose tolerance test (FSIVGTT) for use in unhandled mice. We validated the conscious FSIVGTT against the euglycemic clamp for measuring Si in lean and obese mice. Insulin-resistant mice had increased first-phase insulin secretion, decreased Sg, and a reduced DI, qualitatively similar to humans. Intriguingly, although insulin secretion explained most of the variation in glucose disposal in lean mice, Sg and the DI more strongly predicted glucose disposal in obese mice. DI curves identified individual diet-induced obese (DIO) mice as having compensated or decompensated insulin secretion. Conscious FSIVGTT opens the door to apply mouse genetics to the determinants of in vivo insulin secretion, Sg, and DI, and further validates the mouse as a model of metabolic disease.

Biomarkers in Type 2 diabetes: improving risk stratification with the PreDx ® Diabetes Risk Score

Type 2 diabetes is a chronic, debilitating and often deadly disease that has reached epidemic proportions. The onset of diabetes can be delayed or prevented in high-risk individuals by diet and lifestyle changes and medications, and hence a key element for addressing the diabetes epidemic is to identify those most at risk of developing diabetes so that preventative measures can be effectively focused. The PreDx(®) Diabetes Risk Score is a multimarker tool for assessing a patient's risk of developing diabetes within the next 5 years. Requiring a simple blood draw using standard sample collection and handling procedures, the PreDx Diabetes Risk Score is easily implemented in clinical practice and provides an assessment of diabetes risk that is superior to other measures, including fasting plasma glucose, glycated hemoglobin, measures of insulin resistance and other clinical measures. In this article, we provide an overview of the PreDx Diabetes Risk Score.

Glucose-incretin interaction revisited

Pancreatic beta cell dysfunction is pivotal to the development of diabetes, and restoration of insulin action is of primary importance. Here, we present a review of the mechanism of insulin secretion by pancreatic beta cells and discuss the mutual interaction of signaling pathways in stimulus-secretion coupling to better understand the scientific basis of pharmacological treatment for insulin secretion deficiency. Glucose stimulates insulin secretion via membrane depolarization by closure of ATP-sensitive K(+) channels (K(ATP) channels) and opening of L-type voltage-dependent Ca(2+) channels. The resultant elevation of cytosolic free Ca(2+) triggers insulin exocytosis. This is termed the "K(ATP)-dependent pathway" and is shared by sulfonylurea, which closes K(ATP) channels. Glucose also stimulates insulin release independent of its action on K(ATP) channels. This is referred to as the "K(ATP)-independent pathway," the molecular basis of which remains elusive. In the pancreatic beta cell, incretin hormones increase cAMP level, which enhances glucose-stimulated insulin release by protein kinase A-dependent and -independent mechanisms. Importantly, cAMP does not directly augment Ca(2+)-stimulated insulin release per se. The stimulatory level of ambient glucose is an absolute requirement for incretin to enhance insulin release. Therefore, incretin/cAMP enhances K(ATP)-independent insulinotropic action of glucose. The robust glucose-lowering effect of DPP4 inhibitor add-on in diabetic patients with sulfonylurea secondary failure is intriguing. With the clinical availability of DPP4 inhibitor and GLP-1 mimetics, the importance of the interactions between cAMP signaling and K(ATP) channel-independent actions of glucose is reappraised.

Disposition index, glucose effectiveness, and conversion to type 2 diabetes: the Insulin Resistance Atherosclerosis Study (IRAS)

OBJECTIVE

Disposition index (DI) and glucose effectiveness (S(G)) are risk factors for diabetes. However, the effect of DI and S(G) on future diabetes has not been examined in large epidemiological studies using direct measures.

RESEARCH DESIGN AND METHODS

Insulin sensitivity index (S(I)), acute insulin response (AIR), and S(G) were measured in 826 participants (aged 40-69 years) in the Insulin Resistance Atherosclerosis Study (IRAS) by the frequently sampled intravenous glucose tolerance test. DI was expressed as S(I) x AIR. At the 5-year follow-up examination, 128 individuals (15.5%) had developed diabetes.

RESULTS

The area under the receiver operating characteristic curve of a model with S(I) and AIR was similar to that of DI (0.767 vs. 0.774, P = 0.543). In a multivariate logistic regression model that included both DI and S(G), conversion to diabetes was predicted by both S(G) (odds ratio x 1 SD, 0.61 [0.47-0.80]) and DI (0.68 [0.54-0.85]) after adjusting for demographic variables, fasting and 2-h glucose concentrations, family history of diabetes, and measures of obesity. Age, sex, race/ethnicity, glucose tolerance status, obesity, and family history of diabetes did not have a significant modifying impact on the relation of S(G) and DI to incident diabetes.

CONCLUSIONS

The predictive power of DI is comparable to that of its components, S(I) and AIR. S(G) and DI independently predict conversion to diabetes similarly across race/ethnic groups, varying states of glucose tolerance, family history of diabetes, and obesity.

Metabolic dysfunction in women with bipolar disorder: the potential influence of family history of type 2 diabetes mellitus

OBJECTIVE

Overweight/obesity, insulin resistance (IR), and other types of metabolic dysfunction are common in patients with bipolar disorder (BD); however, the pathophysiological underpinnings of metabolic dysfunction in BD are not fully understood. Family history of type 2 diabetes mellitus (FamHxDM2), which has been shown to have deleterious effects on metabolic function in the general population, may play a role in the metabolic dysfunction observed in BD.

METHODS

Using multivariate analysis of variance, the effects of BD illness and/or FamHxDM2 were examined relative to metabolic biomarkers in 103 women with BD and 36 healthy, age-matched control women.

RESULTS

As a group, women with BD had higher levels of fasting plasma insulin (FPI) and fasting plasma glucose (FPG), higher homeostatic assessment of IR (HOMA-IR) scores, body mass index (BMI), waist circumference (WC), and hip circumference (HC) compared to control women. FamHxDM2 was associated with significantly worse metabolic biomarkers among women with BD but not among healthy control women. Among women with BD, there was a significant main effect of FamHxDM2 on FPI, HOMA-IR, BMI, WC, and HC, even after controlling for type of BD illness, duration of medication exposure, and depression severity. Metabolic biomarkers were not influenced by use of weight-liable psychotropic medication (WLM), even after controlling for type of BD illness, duration of medication exposure, and depression severity.

CONCLUSIONS

Women with BD have overall worse metabolic biomarkers than age-matched control women. The use of WLM, duration of medication use, type of BD illness, and depression severity did not appear to be associated with more pronounced metabolic dysfunction. FamHxDM2 may represent a risk factor for the development of IR in women with BD. Further, focused studies of the endocrine profiles of families of BD patients are needed.

The role of mitochondria in the pathogenesis of type 2 diabetes

The pathophysiology of type 2 diabetes mellitus (DM) is varied and complex. However, the association of DM with obesity and inactivity indicates an important, and potentially pathogenic, link between fuel and energy homeostasis and the emergence of metabolic disease. Given the central role for mitochondria in fuel utilization and energy production, disordered mitochondrial function at the cellular level can impact whole-body metabolic homeostasis. Thus, the hypothesis that defective or insufficient mitochondrial function might play a potentially pathogenic role in mediating risk of type 2 DM has emerged in recent years. Here, we summarize current literature on risk factors for diabetes pathogenesis, on the specific role(s) of mitochondria in tissues involved in its pathophysiology, and on evidence pointing to alterations in mitochondrial function in these tissues that could contribute to the development of DM. We also review literature on metabolic phenotypes of existing animal models of impaired mitochondrial function. We conclude that, whereas the association between impaired mitochondrial function and DM is strong, a causal pathogenic relationship remains uncertain. However, we hypothesize that genetically determined and/or inactivity-mediated alterations in mitochondrial oxidative activity may directly impact adaptive responses to overnutrition, causing an imbalance between oxidative activity and nutrient load. This imbalance may lead in turn to chronic accumulation of lipid oxidative metabolites that can mediate insulin resistance and secretory dysfunction. More refined experimental strategies that accurately mimic potential reductions in mitochondrial functional capacity in humans at risk for diabetes will be required to determine the potential pathogenic role in human insulin resistance and type 2 DM.

Insulin resistance, beta-cell dysfunction, and conversion to type 2 diabetes in a multiethnic population: the Insulin Resistance Atherosclerosis Study

OBJECTIVE

Insulin resistance and beta-cell function are major predictors of type 2 diabetes, but studies using direct methods of insulin resistance and secretion are few and relatively small. Furthermore, the strength of these associations has not been tested in different ethnic groups and various states of glucose tolerance, family history of diabetes, and obesity.

RESEARCH DESIGN AND METHODS

Predictors of incident diabetes were evaluated in Hispanic, non-Hispanic white, and African American participants in the Insulin Resistance Atherosclerosis Study (aged 40-69 years). In 557 participants with normal glucose tolerance and 269 with impaired glucose tolerance (IGT), insulin sensitivity (insulin sensitivity index [S(I)]) and first-phase insulin secretion (acute insulin response [AIR]) were directly measured using the frequently sampled intravenous glucose tolerance test.

RESULTS

At the 5-year follow-up examination, 128 (15.5%) individuals had developed diabetes. Both S(I) (odds ratio x 1 SD 0.50 [95% CI 0.37-0.68]) and AIR (0.51 [0.40-0.65]) were independent predictors of incident diabetes even after adjustment for age, sex, ethnicity, center, IGT, family history of diabetes, and BMI. The strength of the relation of S(I) and AIR to incident diabetes was not significantly affected by potential interactions of age, sex, ethnicity, glucose tolerance, BMI, or family history of diabetes (P > or = 0.15).

CONCLUSIONS

Both insulin sensitivity and beta-cell function predict conversion to diabetes in different ethnic groups and various states of glucose tolerance, family history of diabetes, and obesity. The prevention of type 2 diabetes should focus on interventions that improve both insulin resistance and insulin secretion.

Validation of a multimarker model for assessing risk of type 2 diabetes from a five-year prospective study of 6784 Danish people (Inter99)

BACKGROUND

Improved identification of subjects at high risk for development of type 2 diabetes would allow preventive interventions to be targeted toward individuals most likely to benefit. In previous research, predictive biomarkers were identified and used to develop multivariate models to assess an individual's risk of developing diabetes. Here we describe the training and validation of the PreDx Diabetes Risk Score (DRS) model in a clinical laboratory setting using baseline serum samples from subjects in the Inter99 cohort, a population-based primary prevention study of cardiovascular disease.

METHODS

Among 6784 subjects free of diabetes at baseline, 215 subjects progressed to diabetes (converters) during five years of follow-up. A nested case-control study was performed using serum samples from 202 converters and 597 randomly selected nonconverters. Samples were randomly assigned to equally sized training and validation sets. Seven biomarkers were measured using assays developed for use in a clinical reference laboratory.

RESULTS

The PreDx DRS model performed better on the training set (area under the curve [AUC] = 0.837) than fasting plasma glucose alone (AUC = 0.779). When applied to the sequestered validation set, the PreDx DRS showed the same performance (AUC = 0.838), thus validating the model. This model had a better AUC than any other single measure from a fasting sample. Moreover, the model provided further risk stratification among high-risk subpopulations with impaired fasting glucose or metabolic syndrome.

CONCLUSIONS

The PreDx DRS provides the absolute risk of diabetes conversion in five years for subjects identified to be "at risk" using the clinical factors.

Preventing type 2 diabetes: public health implications for women with a history of gestational diabetes mellitus

There is now strong evidence that lifestyle modification can prevent or delay the development of type 2 diabetes mellitus in high-risk individuals. Women with gestational diabetes mellitus are at increased risk for type 2 diabetes and so are candidates for prevention programs. We review literature on type 2 diabetes risk in women with gestational diabetes, examine current recommendations for postpartum and long-term follow-up, and summarize findings from a 2007 expert-panel meeting. We found data to support that women with gestational diabetes have an increase in risk of type 2 diabetes comparable in magnitude with that of individuals with impaired glucose tolerance and/or impaired fasting glucose and that prevention interventions likely are effective in this population. Current recommendations from leading organizations on follow-up of women after delivery are conflicting and compliance is poor. Clinicians and public health workers face numerous challenges in developing intervention strategies for this population. Translation research will be critical in addressing this important public health issue.

Are we losing the battle against cardiometabolic disease? The case for a paradigm shift in primary prevention

Background

Cardiovascular and diabetic disease are the leading and preventable causes of death worldwide. The currently prognosticated dramatic increase in disease burden over the next two decades, however, bespeaks a low confidence in our prevention ability. This conflicts with the almost enthusiastic reporting of study results, which demonstrate substantial risk reductions secondary to simple lifestyle changes.

Discussion

There is a case to be made for a disregard of the difference between statistical significance and clinical relevance of the reported data. Nevertheless, lifestyle change remains the main weapon in our battle against the epidemic of cardiometabolic disease. But along the way from risk screening to intervention to maintenance the compound inefficiencies of current primary preventive strategies marginalize their impact.

Summary

Unless we dramatically change the ways in which we deploy preventive interventions we will inevitably lose the battle. In this paper we will argue for three provocative strategy changes, namely (a) the disbanding of screening in favor of population-wide enrollment into preventive interventions, (b) the substitution of the current cost utility analysis for a return-on-investment centered appraisal of interventions, and (c) the replacement of standardized programs modeled around acute care by individualized and perpetual interventions.

Genetic determinants and molecular pathways in the pathogenesis of Type 2 diabetes

T2DM (Type 2 diabetes mellitus) has reached epidemic proportions worldwide, exerting major health consequences at an individual and public health level alike. Unfortunately, the molecular pathophysiology of diabetes remains incompletely understood, impairing progress towards more effective prevention and treatment strategies. Although the rapid increase in the prevalence of insulin resistance and T2DM over the past several decades highlights a major environmental contribution related to overnutrition, obesity and inactivity, susceptibility is likely to reflect individual differences in complex gene-environment interactions. In the present review, we focus on mediators of genetic and environmental risk for T2DM at a molecular level.

Glucose and lipid disturbances after 1 year of antipsychotic treatment in a drug-naïve population

OBJECTIVE

This study examined the main metabolic side effects induced by antipsychotic treatment in a cohort of first episode drug-naïve subjects after the first year of treatment.

METHODS

A randomized, open-label, prospective clinical trial was conducted. Participants were 164 consecutive subjects included in a first episode program and never treated with antipsychotic medication. Patients were assigned to haloperidol, olanzapine or risperidone. The main outcome measures were changes at 1 year in fasting glucose parameters (glucose, insulin levels and insulin resistance index) and changes in fasting lipid parameters (total cholesterol, triglycerides, LDL cholesterol, HDL cholesterol).

RESULTS

144 of the total sample were evaluated at 1 year. There was a statistically significant increase in the mean values of insulin levels, insulin resistance index, total cholesterol, LDL-cholesterol and triglycerides. No pathological values in fasting glucose plasma levels were found at baseline and there were no changes after 1 year. Weight gain was positively correlated with changes in insulin levels, insulin resistance index and triglyceride levels. We did not detect statistically significant differences between treatments in any of the parameters evaluated.

CONCLUSIONS

Fasting glycaemia and insulin concentrations at baseline do not support the hypothesis that schizophrenia is associated with an underlying abnormality in glucose metabolism. The changes in insulin and lipid parameters at 1 year seem to be related to the magnitude of weight gain. There were no significant differences between haloperidol, olanzapine and risperidone concerning metabolic adverse effects after the first year of treatment.

Family history of diabetes impacts on interactions between minimal model estimates of insulin sensitivity and glucose effectiveness

AIMS/HYPOTHESIS

Insulin resistance and glucose effectiveness (S(G)) are major determinants of glucose tolerance and independently predict the development of type 2 diabetes in individuals with a family history of disease. We examined the inter-relationship between insulin sensitivity (S(I)) and S(G) in offspring of two parents with type 2 diabetes and in individuals with no family history of diabetes.

METHODS

Fifty non-diabetic individuals, including 26 offspring of two type 2 diabetic parents (family history, FH+) and 24 with no family history of diabetes (FH-) similar in gender, age, ethnicity and body mass index (BMI) were studied. Each subject underwent a 100-g oral glucose tolerance test (OGTT) and insulin modified frequently sampled intravenous glucose tolerance, analysed using the Bergman's minimal model (MINMOD).

RESULTS

Thirteen subjects of the FH+ group and nine of the FH- group had impaired glucose tolerance (IGT). S(I) and S(G) were independent variables in the FH+ group, while they correlated highly with each other in the FH- group (r = 0.69, p = 0.0002). The relationship between S(I) and S(G) persisted when analysing the IGT and normal glucose tolerance subgroups separately, demonstrating that these associations were not because of differences in glycaemia. Consistently, S(G) strongly correlated with additional measures of insulin resistance only in the FH- group, including fasting insulin (r = 0.56, p = 0.004), homeostasis model assessment of insulin resistance (r = 0.57 p = 0.003) and BMI (r = 0.66, p = 0.0004).

CONCLUSIONS

These results demonstrate that familial factors impart important physiological differences in the inter-relationship between insulin-dependent and insulin-independent glucose disposal, which may be important in modulating risk for development of disease.

Adiponectin and its response to thiazolidinediones are associated with insulin-mediated glucose metabolism in type 2 diabetic patients and their first-degree relatives

Patients with type 2 diabetes (T2D) and their first-degree relatives (FDRs) are characterized by hypoadiponectinaema and insulin resistance. In T2D patients, plasma adiponectin and insulin sensitivity (SI) increase in response to thiazolidinediones (TZDs). These findings suggest a role for adiponectin in the regulation of SI. We studied the relationship between plasma adiponectin and glucose and lipid metabolism and the effect of troglitazone (200 mg/day) for 12 weeks in 19 normoglycaemic, obese FDR and 20 obese T2D patients, using euglycaemic-hyperinsulinaemic clamps, glycolytic flux calculations and indirect calorimetry. Plasma adiponectin was similar in both groups, despite higher glucose disposal (Rd), glucose oxidation and glycolytic flux and lower lipid oxidation during insulin stimulation in FDR compared with T2D patients. Plasma adiponectin correlated with insulin-stimulated Rd, non-oxidative glucose disposal (NOGD), glucose storage and SI in both groups after adjustment for sex and body fat. The troglitazone-mediated upregulation of plasma adiponectin was associated with increased insulin-stimulated Rd, NOGD and glucose storage in both groups. No effect on endogenous glucose production was observed. In FDR, plasma adiponectin correlated with insulin-stimulated glycogen synthase activity and the troglitazone-induced increase in plasma adiponectin correlated with the improvement in insulin-stimulated Rd and SI after adjustment for sex and body fat. In conclusion, plasma adiponectin in weight-matched FDR and T2D patients is comparably low and correlates with insulin-mediated glucose uptake and storage. Moreover, these data provide evidence for an adiponectin-dependent insulin-sensitizing effect of TZDs at an early stage before development of T2D and that this effect is exerted mainly on insulin-mediated glucose metabolism.

Pre-teen insulin resistance predicts weight gain, impaired fasting glucose, and type 2 diabetes at age 18-19 y: a 10-y prospective study of black and white girls

BACKGROUND

Identifying early pre-teen predictors of adolescent weight gain and the development of impaired fasting glucose (IFG) and type 2 diabetes (T2DM) at age 18-19 y could provide avenues for prevention.

OBJECTIVE

We evaluated possible pre-teen predictors for development of IFG, T2DM, and changes in body mass index at age 18-19 y in black and white girls.

DESIGN

In a prospective cohort study, body habitus and fasting insulin and glucose were measured at ages 9-10 and 18-19 y, and multiple 3-d diet records were collected. Factors predicting 10-y change in body mass index and development of IFG and T2DM together were assessed.

RESULTS

In multivariate analyses, 10-y change in homeostatic model assessment of insulin resistance (HOMA-IR) and the age 9-10 y HOMA-IR x percentage of calories from fat interaction were positive predictors of 10-y changes in body mass index. At age 18-19 y, there were 5 incident cases of T2DM, 37 cases of IFG, and 597 noncases. Age 9-10 y IFG and HOMA-IR (or insulin), 10-y change in HOMA-IR (or insulin), and the age 9-10 y insulin x total caloric intake interaction predicted IFG and T2DM at age 18-19 y.

CONCLUSIONS

Pre-teen IFG, insulin resistance (and insulin), and rapidly increasing insulin resistance during adolescence identifies girls who are at greater risk of future IFG and T2DM. In addition, insulin resistance, interacting with high-fat diets, identifies girls who are at risk of greater weight gain. These findings could open avenues to primary prevention of obesity, IFG, and T2DM in children.

An observational study of reduction of insulin resistance and prevention of development of type 2 diabetes mellitus in women with polycystic ovary syndrome treated with metformin and diet

Our first specific aim in an observational study of 431 nondiabetic women with polycystic ovary syndrome (PCOS), aged >or=20 years and with >or=11 months follow-up on metformin diet, was to prospectively assess relationships between pretreatment glucose and insulin resistance (IR) and the development of type 2 diabetes mellitus (T2DM) or gestational diabetes (GD). Our second specific aim was to determine whether development of T2DM and GD was independently associated with lesser reduction of IR on metformin diet when compared with women who remained free of T2DM and GD. Women with body mass index <25 kg/m(2) and those with body mass index >or=25 kg/m(2) were, respectively, instructed in a 2000- or 1500-cal/d, high-protein (26% of calories), low-carbohydrate (44%) diet, with 30% of calories as fat and a polyunsaturate-saturate ratio of 2:1. Three groups of women with PCOS were categorized: (a) 17 with no previous GD, who developed T2DM on metformin diet (mean +/- SD follow-up, 49 +/- 33 months), (b) 401 with no previous GD and free of T2DM on metformin diet (follow-up, 38 +/- 25 months), and (c) 13 with either previous GD or GD on metformin diet (follow-up, 38 +/- 25 months). On metformin diet, women who developed T2DM vs those who remained free of T2DM had higher pretreatment glucose (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.03-1.16; P = .003) and homeostasis model assessment of insulin resistance (HOMA-IR) (OR, 1.22; 95% CI, 1.04-1.42; P = .01), and less reduction of HOMA-IR (OR, 0.82; 95% CI, 0.72-0.92; P = .0008). On metformin diet, women either with previous GD or who developed GD vs those who remained free of T2DM had less reduction of HOMA-IR (OR, 0.88; 95% CI, 0.78-0.99; P = .03). By repeated-measures analysis, on metformin diet, women who did not develop T2DM had reduction in HOMA-IR (P < .0001), with the slope of this curve different (P = .002) from the unchanged IR exhibited by women who developed T2DM and different (P = .017) from an increased IR slope (P = .049) in women who had GD. In women with PCOS, pretreatment glucose and IR, and lesser reduction in IR on metformin diet were associated with T2DM and GD.

Glucose turnover and intima media thickness of internal carotid artery in type 2 diabetes offspring

BACKGROUND

First-degree offspring (OFF) of type 2 diabetic (T2DM) patients bear a approximately 40% lifetime risk of developing T2DM. They are insulin resistant and carry a risk of premature atherosclerosis, the extent of which can be estimated by intima media thickness (IMT) of the carotid artery (CA). Thus, this study examines parameters of glucose and lipid metabolism, insulin sensitivity, beta cell function (BCF) and IMT with their interrelationships in middle-aged OFF.

MATERIALS AND METHODS

T2DM-OFF (n = 18, 14f/4m, 45.6 +/- 2.1 years, BMI: 26 +/- 1 kg m(-2)) were compared with 18 matching humans without a family history of diabetes (CON; 14f/4m, 44.5 +/- 2.1 years, BMI: 24 +/- 1 kg m(-2); each P > 0.30), all with normal glucose tolerance as tested by three-hour (75 g) oral glucose tolerance tests (OGTT). Two-hour hyperinsulinaemic (40 mU min(-1).m(-2))isoglycaemic clamp tests were performed with simultaneous measurement of endogenous glucose (D-[6,6-(2)H(2)]glucose) production (EGP). IMT [internal (ICA), common CA, and bulb] were measured sonographically. BCF was assessed by Adaptation Index (AI).

RESULTS

Before and during OGTT, both groups were similar in plasma glucose, insulin, C-peptide and free fatty acids (FFA), whereas OFF showed ~30% lower (P < 0.03) fasting plasma triglycerides before OGTT. During hyperinsulinaemic clamps, insulin sensitivity was approximately 38% lower (P < 0.03) in OFF who showed higher plasma FFA (44 +/- 9 micromol L(-1)) than CON (26 +/- 3 micromol L(-1), P < 0.05) after 90 min. EGP was similar in both groups. OFF had 38% (P < 0.007) reduced AI. ICA-IMT was approximately 18% higher in OFF (P < 0.002), but did not correlate with insulin sensitivity.

CONCLUSION

The data obtained show middle-aged T2DM-OFF with normal glucose tolerance displaying reduced total insulin sensitivity and impaired beta cell function, which relates to impaired insulin-dependent suppression of plasma FFA and increased ICA-IMT.

Family history and prevalence of diabetes in the U.S. population: the 6-year results from the National Health and Nutrition Examination Survey (1999-2004)

OBJECTIVE

We sought to test the association between stratified levels of familial risk of diabetes and the prevalence of the disease in the U.S. population.

RESEARCH DESIGN AND METHODS

This study includes 16,388 adults interviewed for the National Health and Nutrition Examination Survey between 1999 and 2004. Fasting glucose was available for a subsample of 6,004 participants. Familial risk of diabetes was classified as average, moderate, or high. The prevalence and the odds of having diabetes were estimated for each risk class after accounting for other risk factors.

RESULTS

Overall, 69.8% of the U.S. adults were in the average, 22.7% in the moderate, and 7.5% in the high familial risk for diabetes. The crude prevalence of diabetes for each risk class was 5.9, 14.8, and 30%, respectively. The graded association between familial risk and prevalence of diabetes remained even after accounting for sex, race/ethnicity, age, BMI, hypertension, income, and education. Versus people in the average risk class, independently of other risk factors considered, the odds of having diabetes for people in the moderate and high familial risk categories were, respectively, 2.3 and 5.5 times higher.

CONCLUSIONS

In the U.S. population, family history of diabetes has a significant, independent, and graded association with the prevalence of diabetes. This association not only highlights the importance of shared genes and environment in diabetes but also opens the possibility of formally adding family history to public health strategies aimed at detecting and preventing the disease.

The Clamp-Like Index: a novel and highly sensitive insulin sensitivity index to calculate hyperinsulinemic clamp glucose infusion rates from oral glucose tolerance tests in nondiabetic subjects

OBJECTIVE

Insulin resistance, the underlying pathophysiological mechanism of the metabolic syndrome, can not only predict type 2 diabetes development but also cardiovascular disease. Thus, precise insulin resistance measurement in individuals at risk for metabolic diseases would support clinical risk stratification. However, the gold standard for measuring insulin resistance, the hyperinsulinemic clamp test, is too labor intensive to be performed in large clinical studies/settings.

RESEARCH DESIGN AND METHODS

Using plasma glucose and C-peptide concentrations from oral glucose tolerance tests (OGTTs), we developed the novel "clamp-like index" (CLIX) for insulin sensitivity calculation and compared CLIX to clamp glucose infusion rates (GIR) (100-120 min). We evaluated CLIX in 89 nondiabetic subjects (58 female and 31 male, aged 45 +/- 1 years, BMI 27.5 +/- 0.8 kg/m(2)) who underwent frequently sampled 3-h 75-g OGTTs and 2-h hyperinsulinemic-isoglycemic clamp (40 mU/min per m(2)) tests.

RESULTS

CLIX, calculated as serum creatinine (x0.85 if male)/(mean AUC(glucose) x mean AUC(C-peptide)) x 6,600, was highly correlated (r = 0.670, P < 10(-12)) with and comparable to clamp GIRs(100-120 min). In subgroup analyses, GIRs(100-120 min) were lower (P < 0.005) in type 2 diabetic offspring (6.2 +/- 0.7 mg x min(-1) x kg(-1)) than in sex-, age-, and BMI-matched subjects without a family history of type 2 diabetes (8.6 +/- 0.5 mg x min(-1) x kg(-1)), which was also reflected by CLIX (insulin-resistant offspring 6.4 +/- 0.6 vs. those without a family history of type 2 diabetes 9.0 +/- 0.5; P < 0.002). When compared with normal-weight subjects (GIR 8.8 +/- 0.4 mg x min(-1) x kg(-1); CLIX 9.0 +/- 0.5), both GIRs(100-120 min) and CLIX of obese (5.2 +/- 0.9 mg x min (-1) x kg(-1); 5.7 +/- 0.9) and morbidly obese (2.4 +/- 0.4 mg x min (-1) x kg(-1); 3.3 +/- 0.5) humans were lower (each P < 0.02).

CONCLUSIONS

CLIX, a novel index obtained from plasma OGTT glucose and C-peptide levels and serum creatinine, without inclusion of anthropometrical measures to calculate insulin sensitivity in nondiabetic humans, highly correlates with clamp GIRs and reveals even slight insulin sensitivity alterations over a broad BMI range and is as sensitive as the hyperinsulinemic clamp test.

Pioglitazone has anti-inflammatory effects in patients with Type 2 diabetes

BACKGROUND

Type 2 diabetes is characterized by increased acute phase serum proteins. They are also risk factors for cardiovascular disease. We wanted to study how improvement of glycemic control with pioglitazone or glibenclamide affects their serum concentrations.

MATERIALS AND METHODS

A total of 59 patients with Type 2 diabetes (age 57.3+/-1.2 yr, glycosylated hemoglobin (HbA1c) 8.3+/-0.7%, body mass index (BMI) 31.4+/-0.8 kg/m2) participated in the study. They were previously treated either with diet alone or in combination with one oral antihyperglycemic medicine. After a 1-week lead-in period on diet only, the patients were randomized to pioglitazone or glibenclamide. Blood samples for alpha-1-acid glycoprotein (A1GP), Creactive protein (CR P) and serum amyloid A (SAA) were taken before the treatments and during the therapy after 20 and 52 weeks.

RESULTS

Baseline A1GP correlated with CR P (r=0.70, p<0.001) and fasting glucose (r=0.32, p<0.02). Baseline CR P correlated with HbA1c (r=0.26, p<0.05) and insulin (r=0.37, p<0.01). The anti-hyperglycemic effect was comparable with HbA1c levels decreasing both in the pioglitazone (from 8.18+/-0.09% to 7.63+/-0.17%, p<0.01) and glibenclamide (from 8.35+/-0.12% to 7.77+/-0.16%, p<0.01) groups. Pioglitazone treatment was associated with a reduction in A1GP at 20 weeks (p<0.001) and at 52 weeks (p<0.05) as compared to baseline. The significance remained also after comparison to glibenclamide therapy (p<0.001 and p<0.05, 20 and 52 weeks respectively). CR P was also more reduced in the pioglitazone group at 20 weeks of treatment (p<0.05).

CONCLUSIONS

Inflammatory factors and markers of hyperglycemia are associated in patients with Type 2 diabetes. Pioglitazone treatment results in reduced A1GP concentration suggesting an anti-inflammatory effect.

The effect of exercise, training, and inactivity on insulin sensitivity in diabetics and their relatives: what is new?

Insulin resistance is a hallmark characteristic of type 2 diabetes. However, in healthy first-degree relatives of type 2 diabetics, insulin resistance is often present years before glucose intolerance or diabetes becomes clinically manifest. The mechanisms of insulin resistance involve conditions leading to an increased supply of fatty acids (e.g., high energy intake, obesity) and conditions in which the degradation/oxidation of muscular fatty acids is impaired. Several large-scale studies have documented the fact that increased physical activity can reduce or at least postpone the development of type 2 diabetes, and low physical fitness is a clear independent risk factor for the development of type 2 diabetes. The mechanisms responsible for the improvement in insulin sensitivity after exercise training have been studied extensively, but are not fully understood. This review focuses on insulin resistance in skeletal muscle and, in particular, its relation to changes in aerobic fitness in type 2 diabetics and their first-degree relatives.