The Relationship of Metabolic Syndrome Traits with Beta-Cell Function and Insulin Sensitivity by Oral Minimal Model Assessment in South Asian and European Families Residing in the Netherlands

Insulin sensitivity, disposition index and insulin clearance in cystic fibrosis: a cross-sectional study

AIMS/HYPOTHESIS

The aim of this study was to investigate insulin secretion, insulin sensitivity, disposition index and insulin clearance by glucose tolerance status in individuals with cystic fibrosis (CF) and exocrine pancreatic insufficiency.

METHODS

In a cross-sectional study, we conducted an extended (ten samples) OGTT in individuals with pancreatic-insufficient CF (PI-CF). Participants were divided into normal glucose tolerance (NGT), early glucose intolerance (EGI), impaired glucose tolerance (IGT) and CF-related diabetes (CFRD) groups. We used three different oral minimal models to assess insulin secretion, insulin sensitivity and insulin clearance during the OGTT. We evaluated insulin secretion using total secretion (Φ total), first-phase secretion (Φ dynamic) and second-phase secretion (Φ static) from the model, and we estimated the disposition index by multiplying Φ total and insulin sensitivity.

RESULTS

Among 61 participants (NGT 21%, EGI 33%, IGT 16%, CFRD 30%), insulin secretion indices (Φ total, dynamic and static) were significantly lower in the CFRD group compared with the other groups. Insulin sensitivity declined with worsening in glucose tolerance (p value for trend <0.001) and the disposition index declined between NGT and EGI and between IGT and CFRD. Those with CFRD had elevated insulin clearance compared with NGT (p=0.019) and low insulin secretion (Φ total) was also associated with high insulin clearance (p<0.001).

CONCLUSIONS/INTERPRETATION

In individuals with PI-CF, disposition index declined with incremental impairment in glucose tolerance due to a reduction in both insulin secretion and insulin sensitivity. Moreover in CF, reduced insulin secretion was associated with higher insulin clearance.

Metabolic Syndrome and Chronic Disease Risk in South Asian Immigrants: A Review of Prevalence, Factors, and Interventions

South Asians (SAs) are among the fastest-growing ethnic groups in the U.S. Metabolic syndrome (MetS) is a condition that is characterized by multiple health factors that increase the risk for chronic diseases, such as cardiovascular disease (CVD) and diabetes. MetS prevalence among SA immigrants ranges from 27-47% in multiple cross-sectional studies using different diagnostic criteria, which is generally higher compared to other populations in the receiving country. Both genetic and environmental factors are attributed to this increased prevalence. Limited intervention studies have shown effective management of MetS conditions within the SA population. This review reports MetS prevalence in SAs residing in non-native countries, identifies contributing factors, and discusses ways to develop effective community-based strategies for health promotion targeting MetS among SA immigrants. There is a need for more consistently evaluated longitudinal studies to facilitate the development of directed public health policy and education to address chronic diseases in the SA immigrant community.

Higher systolic blood pressure is specifically associated with better islet beta-cell function in T2DM patients with high glycemic level

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) usually have higher blood viscosity attributed to high blood glucose that can decrease blood supply to the pancreas. A mild increase in blood pressure (BP) has been reported as a potential compensatory response that can maintain blood perfusion in the islet. However, how BP influences beta-cell function in T2DM subjects remains inconsistent. This study aimed to examine the relationship between BP and beta-cell function in patients with T2DM under different HbA1c levels.

METHODS

This is a cross-sectional study of 615 T2DM patients, whose clinical data were extracted from hospital medical records. Beta-cell function was assessed by insulin secretion-sensitivity index-2 (ISSI2). Multivariable linear regression analysis and restricted cubic splines (RCS) analysis were performed to identify the association between systolic BP (SBP) and ISSI2. Mediation analysis was performed to determine whether higher SBP could reduce blood glucose by enhancing beta-cell function.

RESULTS

After adjustment of potential confounders, in participants with HbA1c ≥ 10%, the SBP between 140 to150 mmHg had the highest log ISSI2 (b = 0.227, 95% CI 0.053-0.402), an association specific to participants with < 1 year duration of diabetes. RCS analyses demonstrated an inverted U-shaped association between SBP and ISSI2 with the SBP at 144 mmHg corresponding to the best beta-cell function. This higher SBP was "paradoxically" associated with lower 2 h postprandial blood glucose (PBG) when SBP < 150 mmHg that was almost exclusively mediated by ISSI2 (mediating effect = - 0.043, 95%CI - 0.067 to - 0.018; mediating effect percentage = 94.7%, P < 0.01). SBP was however not associated with improvement in ISSI2 or 2 h PBG in participants with HbA1c < 10%.

CONCLUSIONS

In early stage of diabetes, a slightly elevated SBP (140-150 mmHg) was transiently associated with better beta-cell function in T2DM patients with HbA1c ≥ 10% but not in those with HbA1c < 10%.

Bayesian parameter estimation in the oral minimal model of glucose dynamics from non-fasting conditions using a new function of glucose appearance

BACKGROUND AND OBJECTIVE

The oral minimal model (OMM) of glucose dynamics is a prominent method for assessing postprandial glucose metabolism. The model yields estimates of insulin sensitivity and the meal-related appearance of glucose from insulin and glucose data after an oral glucose challenge. Despite its success, the OMM approach has several weaknesses that this paper addresses.

METHODS

A novel procedure introducing three methodological adaptations to the OMM approach is proposed. These are: (1) the use of a fully Bayesian and efficient method for parameter estimation, (2) the model identification from non-fasting conditions using a generalised model formulation and (3) the introduction of a novel function to represent the meal-related glucose appearance based on two superimposed components utilising a modified structure of the log-normal distribution. The proposed modelling procedure is applied to glucose and insulin data from subjects with normal glucose tolerance consuming three consecutive meals in intervals of four hours.

RESULTS

It is shown that the glucose effectiveness parameter of the OMM is, contrary to previous results, structurally globally identifiable. In comparison to results from existing studies that use the conventional identification procedure, the proposed approach yields an equivalent level of model fit and a similar precision of insulin sensitivity estimates. Furthermore, the new procedure shows no deterioration of model fit when data from non-fasting conditions are used. In comparison to the conventional, piecewise linear function of glucose appearance, the novel log-normally based function provides an improved model fit in the first 30 min of the response and thus a more realistic estimation of glucose appearance during this period. The identification procedure is implemented in freely accesible MATLAB and Python software packages.

CONCLUSIONS

We propose an improved and freely available method for the identification of the OMM which could become the future standardard for the oral minimal modelling method of glucose dynamics.

Ethnicity and Type 2 diabetes in the UK

Type 2 diabetes is a major UK public health priority. Among minority ethnic communities, the prevalence is alarmingly high, approximately three to five times higher than in the white British population. Particularly striking is the earlier onset of Type 2 diabetes, which occurs some 10-12 years younger, with a significant proportion of cases being diagnosed before the age of 40 years. This review focuses on the UK context and Type 2 diabetes in adult populations, exploring the available evidence regarding the complex interplay of biological, lifestyle, social, clinical and healthcare system factors that are known to drive these disparities.