Poster Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2014

The relationship between fat mass, insulin sensitivity and insulin secretion varies between Caucasian, Indian-Subcontinental and Oriental women after a pregnancy complicated by gestational diabetes. (#271)

Jaime Lin 1 , Allison Sigmund 2 , Susan Hendon 2 , Tien-Ming Hng 2 , Jane Zhang 2 , Mark McLean 1 , Sue-Lynn Lau 1
  1. University of Western Sydney, School of Medicine, NSW, Australia
  2. Endocrinology, Blacktown Hospital, Blacktown, NSW , Australia

INTRODUCTION: In clinical practice, phenotypic differences are observed between women with gestational diabetes (GDM) from different ethnicities. Caucasian women who develop GDM have higher mean BMI than those who remain euglycaemic. In our cohort, this difference was not observed in Orientals. We explored the relationship between BMI, adiposity and glucose metabolism in different ethnicities after GDM-pregnancy.

METHODS: Women in a GDM cohort study were examined at 10-12 weeks postpartum using anthropometry and DEXA-derived measures of body composition. Fat mass index (FMI) was calculated as (bodyfat-kg)/(height-m2). Central fat percentage (CF%) was computed using the Lunar Prodigy custom tool. Indices of insulin secretion(InSec) (oralDI:{∆insulin(30-0 mins)/ ∆glucose(30-0 mins)]x1/fasting insulin) and insulin sensitivity (InSens) (Matsuda Index) were derived from the 0, 30 and 120 minute time-points of 75g OGTT. Data relationships were examined using Spearman’s Rho correlations and one-way ANOVA.

RESULTS: 30 Caucasian, 38 Subcontinental and 20 Oriental women participated. Mean BMI was highest in Caucasians > Subcontinentals > Orientals (31.5 vs 27.5 vs 24.9 respectively, p<0.01). FMI (14.5 vs 12.1 vs 9.9) and waist circumference followed a similar pattern (101.6cm vs 94.9cm vs 88.1cm respectively, p<0.05 for all). However, no significant difference in CF% was observed between any groups (42.9% vs 43.6% vs 40%). The IGT rate was similar across ethnic groups (16-20%ns). 1 subcontinental woman with diabetes was excluded. In Caucasians, FMI negatively correlated with lnSens(Matsuda Index) (r=-0.373, p=0.04) but not with lnSec(oralDI). In Subcontinentals, FMI negatively correlated with lnSec(oral DI) (r=-0.449, p<0.01) but not InSens(Matsuda Index). In Orientals, FMI negatively correlated with both lnSens(Matsuda Index) (r=-0.671, p=0.001) and lnSec(oralDI) (r=-0.699, p=0.001). CF% followed the same significant relationships. Matsuda Index and OralDI did not differ between ethnic groups.

CONCLUSION: Despite significant differences in anthropometry and FMI, all three groups demonstrated similar accumulation of central fat. In this small sample, the relationship between adiposity, insulin secretion and sensitivity appears to vary between ethnicities, possibly indicating different pathophysiology for their propensity to diabetes.