Changes in adiposity mediate the associations of diet quality with insulin sensitivity and beta-cell function

Cardiometabolic risk assessment: A school-based study in Brazilian adolescent

BACKGROUND AND AIMS

Recently, new indices combining routine and low-cost anthropometric and biochemical measurements have emerged. Among them, the visceral adiposity index (VAI) and lipid accumulation product (LAP) are being investigated for the prediction of altered blood pressure (BP) and insulin resistance (IR). Therefore, this study aimed to evaluate whether visceral adiposity index (VAI) and height-corrected lipid accumulation product (HLAP) are predictors of cardiometabolic risk in Brazilian adolescents.

METHODS AND RESULTS

Data were obtained from the Cardiovascular Risk in Adolescents (ERICA) study, a cross-sectional, national, multicenter, school-based survey conducted between 2013 and 2014 in Brazil. The sample consisted of 37,815 adolescents aged 12-17 years of both genders attending the last 3 years of elementary or secondary school from public and private schools located in 273 municipalities with more than 100,000 inhabitants. A Poisson regression was performed to verify associations between VAI and HLAP indices and the presence of altered BP and IR according to sex. In addition, receiver operating characteristic curve (ROC) analysis was applied to compare the predictive ability and determine the cut-off points of the VAI and HLAP indices in identifying cardiometabolic risk obtained by altered BP and IR. The prevalences of altered BP and IR were 24.49 % (95 % confidence interval [CI]: 23.14-25.87) and 24.22 % (95 % CI: 22.70-25.80), respectively.

CONCLUSIONS

The VAI and HLAP indices are good predictors of cardiometabolic risk in Brazilian adolescents. HLAP showed better performance in identifying insulin resistance in males.

Deteriorating beta cell function is the dominant determinant of progression from normal glucose tolerance to prediabetes/diabetes in young women following pregnancy

AIMS/HYPOTHESIS

Excess adiposity, insulin resistance and beta cell dysfunction each contribute to the development of prediabetes (impaired glucose tolerance and/or impaired fasting glucose)/diabetes but their comparative impact in relation to one another remains uncertain. We thus ranked their contributions to incident dysglycaemia over the first 5 years postpartum in women reflecting the full spectrum of gestational glucose tolerance (spanning normoglycaemia to gestational diabetes) and hence a range of future diabetic risk.

METHODS

In this study, 302 women with normal glucose tolerance (NGT) on OGTT at 3 months postpartum underwent repeat OGTT at 1 year, 3 years and 5 years, enabling serial assessment of glucose tolerance, insulin sensitivity/resistance (Matsuda index, HOMA-IR) and beta cell function (insulin secretion-sensitivity index-2 [ISSI-2], insulinogenic index [IGI]/HOMA-IR). Determinants of prediabetes/diabetes were ranked by change in concordance index (CCI) of Cox proportional hazard regression models.

RESULTS

Over 5 years of follow-up, 89 women progressed from NGT to prediabetes/diabetes (progressors). At 3 months postpartum, though all women were normoglycaemic, future progressors had higher fasting glucose (p=0.03) and 2 h glucose (p<0.0001) than non-progressors, coupled with higher BMI (p=0.001), greater insulin resistance (both Matsuda index and HOMA-IR, p≤0.02) and poorer beta cell function (both ISSI-2 and IGI/HOMA-IR, p≤0.006). Unlike their peers, progressors exhibited deteriorating beta cell function from 1 year to 5 years (both p<0.0001). On regression analyses, the dominant determinants of progression to prediabetes/diabetes were time-varying ISSI-2 (change in CCI 25.2%) and IGI/HOMA-IR (13.0%), in contrast to time-varying Matsuda index (2.9%) and HOMA-IR (0.5%). Neither time-varying BMI nor waist were significant predictors after adjustment for beta cell function and insulin sensitivity/resistance.

CONCLUSION/INTERPRETATION

Declining beta cell function is the dominant determinant of incident prediabetes/diabetes in young women following pregnancy.

A healthful plant-based eating pattern is longitudinally associated with higher insulin sensitivity in Australian adults

BACKGROUND

A healthful plant-based eating pattern is associated with lower type 2 diabetes risk; however, the association with its preceding state, compromised insulin sensitivity, is less well-established, particularly in younger populations with repeated measures of diet over time.

OBJECTIVE

We aimed to examine the longitudinal relationship between a healthful plant-based eating pattern and insulin sensitivity in young to middle-aged adults.

METHODS

We included 667 participants from the Childhood Determinants of Adult Health (CDAH) study, a population-based cohort in Australia. Healthful plant-based diet index (hPDI) scores were derived from food frequency questionnaire data. Plant foods considered 'healthful' were scored positively (e.g., whole grains, fruit, vegetables), with all remaining foods scored reversely (e.g., refined grains, soft drinks, meat). Updated homeostatic model assessment (HOMA2) estimated insulin sensitivity from fasting insulin and glucose concentrations. We used linear mixed-effects regression to analyse data from two time points: CDAH-1 (2004-06, aged 26-36 years) and CDAH-3 (2017-19, aged 36-49 years). hPDI scores were modelled as between- and within-person effects (i.e., a participant's overall mean and their deviation from said mean at each time point, respectively).

RESULTS

The median follow-up duration was 13 years. In our primary analysis, each 10-unit difference in hPDI score was associated with higher log-HOMA2 insulin sensitivity [95% confidence interval], with between-person (β = 0.11 [0.05, 0.17], P < .001) and within-person effects (β = 0.10 [0.04, 0.16], P = .001). The within-person effect persisted despite accounting for compliance with dietary guidelines. Adjustment for waist circumference attenuated the between-person effect by 70% (P = .26) and the within-person effect by 40% (P = .04).

CONCLUSIONS

In young to middle-aged Australian adults, a healthful plant-based eating pattern (determined using hPDI scores) was longitudinally associated with higher insulin sensitivity, and therefore, potentially lower type 2 diabetes risk later in life.