Strong association between insulin-mediated glucose uptake and the 2-hour, not the fasting plasma glucose concentration, in the normal glucose tolerance range

Serum lipidomics profiles reveal potential lipid markers for prediabetes and type 2 diabetes in patients from multiple communities

OBJECTIVE

Dyslipidemia is a hallmark of diabetes mellitus (DM). However, specific lipid molecules closely associated with the initiation and progression of diabetes remain unclear. We used a pseudotargeted lipidomics approach to evaluate the complex lipid changes that occurred long before the diagnosis of type 2 diabetes mellitus (T2DM) and to identify novel lipid markers for screening prediabetes mellitus (PreDM) and T2DM in patients from multiple communities.

METHODS

Four hundred and eighty-one subjects consisting of T2DM, three subtypes of PreDM, and normal controls (NC) were enrolled as discovery cohort. Serum lipidomic profiles of 481 subjects were analyzed using an ultrahigh performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QqQ-MS)-based pseudotargeted lipidomics method. The differential lipid molecules were further validated in an independent case-control study consisting of 150 PreDM, 234 T2DM and 94 NC.

RESULTS

Multivariate discriminative analyses show that lipidomics data have considerable potential for identifying lipidome differences among T2DM, subtypes of PreDM and NC. Statistical associations of lipid (sub)species display significant variations in 11 lipid (sub)species levels for T2DM and distinctive differences in 8 lipid (sub)species levels between prediabetic and normoglycemic individuals, with further differences in 8 lipid (sub)species levels among subtypes of PreDM. Adjusted for sex, age and BMI, only two lipid (sub)species of fatty acid (FA) and phosphatidylcholine (PC) were associated at p< 0.05 for PreDM (all) and subtypes of PreDM. The defined lipid markers not only significantly improve the diagnostic accuracy of PreDM and T2DM but also effectively evaluating the risk of developing into each subtype of PreDM and T2DM when addition of age, sex, BMI, and FPG, respectively.

CONCLUSIONS

Our findings improve insights into the lipid metabolic complexity and interindividual variations among subtypes of PreDM and T2DM, beyond the well-known differences in dyslipidemia in clinic.

Metabolomic profiles associated with subtypes of prediabetes among Mexican Americans in Starr County, Texas, USA

AIMS/HYPOTHESIS

To understand the complex metabolic changes that occur long before the diagnosis of type 2 diabetes, we investigated differences in metabolomic profiles in plasma between prediabetic and normoglycaemic individuals for subtypes of prediabetes defined by fasting glucose, 2 h glucose and HbA1c measures.

METHODS

Untargeted metabolomics data were obtained from 155 plasma samples from 127 Mexican American individuals from Starr County, TX, USA. None had type 2 diabetes at the time of sample collection and 69 had prediabetes by at least one criterion. We tested statistical associations of amino acids and other metabolites with each subtype of prediabetes.

RESULTS

We identified distinctive differences in amino acid profiles between prediabetic and normoglycaemic individuals, with further differences in amino acid levels among subtypes of prediabetes. When testing all named metabolites, several fatty acids were also significantly associated with 2 h glucose levels. Multivariate discriminative analyses show that untargeted metabolomic data have considerable potential for identifying metabolic differences among subtypes of prediabetes.

CONCLUSIONS/INTERPRETATION

People with each subtype of prediabetes have a distinctive metabolomic signature, beyond the well-known differences in branched-chain amino acids.

DATA AVAILABILITY

Metabolomics data are available through the NCBI database of Genotypes and Phenotypes (dbGaP, accession number phs001166; www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?study_id=phs001166.v1.p1).

Glucose-Mediated Glucose Disposal at Baseline Insulin Is Impaired in IFG

OBJECTIVE

To quantify glucose-mediated glucose disposal with and without basal insulin replacement and insulin-mediated glucose disposal in subjects with impaired fasting glucose (IFG).

RESEARCH DESIGN AND METHODS

We used the hyperglycemic/pancreatic clamp and stepped euglycemic clamp techniques to quantify glucose disposal and suppression of endogenous glucose production (EGP) in those with normal glucose tolerance (NGT; n = 14) and those with IFG (n = 14).

RESULTS

Total body glucose-mediated glucose uptake, measured with the hyperglycemic/pancreatic clamp, was not significantly affected by the basal plasma insulin levels in subjects with IFG and those with NGT. Compared with subjects with NGT, those with IFG had significantly lower glucose-mediated glucose uptake (by 15%) during the hyperglycemic clamp performed with and without basal insulin replacement. In contrast, insulin-mediated glucose disposal was comparable in both groups. The suppression of EGP by hyperglycemia was similar in both groups. However, the suppression of EGP by insulin was attenuated in those with IFG compared with those with NGT.

CONCLUSIONS

The results of the present study have demonstrated that (i) glucose-mediated glucose disposal is impaired in those with IFG; (ii) insulin-mediated glucose uptake in IFG is normal; and (iii) insulin action to suppress EGP is impaired.

A pragmatic lifestyle modification programme reduces the incidence of predictors of cardio-metabolic disease and dysglycaemia in a young healthy urban South Asian population: a randomised controlled trial

BACKGROUND

There is an increasing incidence of type 2 diabetes mellitus (T2DM) in young urban South-Asians. We tested the effect of a pragmatic trimonthly lifestyle modification (LSM) programme (P-LSM) versus a less-intensive 12-monthly control LSM (C-LSM) intervention on a primary composite endpoint of predictors of cardio-metabolic disease (new onset T2DM, hypertension, impaired glucose tolerance (IGT), impaired fasting glycaemia (IFG) and markers of cardio-renal disease) in participants aged 5-40 years with risk factors for T2DM.

METHODS

This was a randomised controlled trial performed at the National Diabetes Centre, Sri-Lanka. We individually randomised 4672 participants at risk of T2DM, of whom 3539 (mean age 22.5 (range 6-40 years, 48% males) received either trimonthly (P-LSM n = 1726) or 12-monthly (C-LSM n = 1813) peer educator advice aimed at reducing weight, improving diet, reducing psychological stress and increasing physical activity.

RESULTS

During a median follow-up of 3 years, the cumulative incidence of the primary endpoint was n = 479 in P-LSM (74 per 1000 person years) vs. 561 in C-LSM (96 per 1000 person years), with an incident rate ratio (IRR) of 0.89 (95% CI 0.83-0.96, P = 0.02). In post hoc analyses, new onset dysglycaemia (T2DM, IFG and IGT), was the major contributor to the composite and was significantly reduced by P-LSM (IRR 0.9, 95% CI 0.83-0.97, P = 0.01). A significant impact of P-LSM on the incidence of the composite endpoint was noted in 1725 participants (P-LSM n = 850, C-LSM n = 875) aged below 18; P-LSM n = 140 (48 per 1000 person years) versus C-LSM n = 174 (55.4 per 1000 person years), with an IRR of 0.83 (95% CI 0.73-0.94, P = 0.004).

CONCLUSIONS

In a young at-risk South-Asian population, a pragmatic LSM programme significantly reduces the incidence of predictors of cardio-metabolic disease. Our results highlight the importance of early intervention in young at-risk subjects.

TRIAL REGISTRATION

World Health Organization international clinical trial registry platform ( SLCTR/2008/003 ). Registration Date: March 28, 2008. Retrospectively registered.

Increased Adipose and Muscle Insulin Sensitivity Without Changes in Serum Adiponectin in Young Female Collegiate Athletes

BACKGROUND

Effects of endurance training on adipose insulin sensitivity in association with body composition, circulating adipokines, and markers of inflammation have been studied less in young Asian subjects.

METHODS

Adipose insulin sensitivity/resistance was compared between 170 female Japanese collegiate athletes and 311 nonathletes (18-24 years), who underwent measurements of serum adipokines, markers of insulin sensitivity, inflammation, and dual-energy X-ray absorptiometry. Two separate subsamples of two groups of women underwent either a 75-gram oral glucose tolerance test or a standardized meal test, but not both.

RESULTS

As compared with nonathletes, athletes, characterized by higher skeletal muscle mass and lower percentage of body fat (both P < 0.001), had lower adipose insulin resistance (IR) (a product of fasting insulin and nonesterified fatty acid (NEFA) and lower leptin/adiponectin ratio (both P < 0.001). Although athletes had lower postmeal/postglucose insulinemia (P = 0.009 and 0.01, respectively), the two groups did not differ in postmeal percentage NEFA suppression and postmeal/postglucose glycemia, suggesting increased insulin sensitivity in adipose tissue and skeletal muscle, respectively. Serum leptin (P < 0.001) and tumor necrosis factor-α (P = 0.01) were lower in athletes, whereas adiponectin and homeostasis model assessment IR did not differ.

CONCLUSIONS

Endurance training was associated with increased insulin sensitivity in adipose tissue as well as skeletal muscle without changes in circulating adiponectin even in young, normal-weight Japanese women.

Prediabetes and risk of diabetes and associated complications: impaired fasting glucose versus impaired glucose tolerance: does it matter?

PURPOSE OF REVIEW

The purpose of this review is to summarize the distinct metabolic and pathophysiologic phenotype of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) and the subsequent clinical implications with regard to future type 2 diabetes mellitus (T2DM) and cardiovascular risk.

RECENT FINDINGS

Both IFG and IGT manifest the two core defects of T2DM, that is, insulin resistance and β-cell dysfunction. However, the site of insulin resistance and shape of β-cell dysfunction differ. These distinct metabolic and pathophysiologic phenotypes explain the greater cardiovascular disease (CVD) risk associated with an increase in the 2-h plasma glucose concentration, that is, IGT compared with an increase in the fasting plasma glucose (FPG) concentration, that is, IFG. Moreover, the increase in future T2DM risk in IFG study participants is, at least in part, explained by the strong correlation between the increase in FPG and the increase in 2-h plasma glucose concentration.

SUMMARY

Last, recent studies have reported the presence of diabetic microvascular complications, that is, retinopathy and neuropathy, at the IGT stage.Thus, a glucose load (e.g. oral glucose tolerance test) is required in study participants with elevated FPG concentration to accurately assess their future risk for T2DM, as well as their risk for CVD to identify the subgroup of IFG who are at greater risk and subject them to an intervention program to decrease their future T2DM and CVD risk.

β-Cell Function and Insulin Sensitivity in Normal Glucose-Tolerant Subjects Stratified by 1-Hour Plasma Glucose Values

AIM

This study was designed to assess β-cell function and insulin sensitivity indices among normal glucose tolerance (NGT) subjects stratified by 1-h plasma glucose (1hPG) values during an oral glucose tolerance test (OGTT).

MATERIALS AND METHODS

One hundred sixty-six NGT subjects underwent a five-point OGTT, and glucose and insulin levels were estimated. We calculated the following indices: (a) β-cell function (homeostasis assessment model-β-cell function [HOMA-β] and Insulinogenic Index [IGI]) and (b) insulin sensitivity (homeostasis assessment model-insulin resistance [HOMA-IR], Matsuda Index, and Insulin Sensitivity Index [ISI]).

RESULTS

NGT subgroups with elevated 1hPG values (i.e., 1hPG ≥143 to <155 mg/dL and 1hPG ≥155 mg/dL) did not differ from those with 1hPG <143 mg/dL by HOMA-β (P = 0.236) but had significantly lower IGIs (367 ± 239 vs. 257 ± 243 vs. 246 ± 239; P = 0.019). With respect to ISIs, HOMA-IR was not significantly different among the groups (P = 0.103). However, the Matsuda Index (11.2 ± 5.0 vs. 7.4 ± 4.8 vs. 5.5 ± 4.9; P < 0.001) and ISI (0.015 ± 0.010 vs. 0.012 ± 0.006 vs. 0.011 ± 0.011; P = 0.028) were significantly lower in subjects with elevated 1hPG values.

CONCLUSIONS

NGT subjects with elevated 1hPG levels have alterations in β-cell function and insulin sensitivity compared with those with normal 1hPG levels.