The impact of ethnicity on glucose homeostasis after gestational diabetes mellitus

The objective of this study was to examine measures of insulin resistance and beta cell function in relation to ethnicity and the development of diabetes after gestational diabetes mellitus (GDM). Glucose homeostasis was assessed during a 75 g oral glucose tolerance test 1–2 years after delivery in 456 women with previous GDM (362 European, 94 non-European; including 41 Arab and 43 Asian women) and 133 control women. Insulin resistance was estimated using homeostasis model assessment of insulin resistance (HOMA-IR). The insulinogenic index (I/G30) and the disposition index [(I/G30)/HOMA-IR] were used to quantify insulin secretion. Women developing diabetes after GDM were characterized by increased HOMA-IR [p = 0.010, adjusted for body mass index (BMI)], whereas the disposition index was decreased in all women with previous GDM irrespective of glucose tolerance, most pronounced in the presence of diabetes (BMI-adjusted p = 1 × 10⁻⁵). Non-European origin was associated with increased HOMA-IR (p = 0.001 vs. European), strengthened by adjustment for BMI in Asian women (p = 0.046 vs. p = 0.016), but eradicated among Arab women (p = 0.004 vs. p = 0.65). Non-European women exhibited an increased frequency of diabetes after GDM (17 % vs. European 4 %, p = 2 × 10⁻⁵). In addition to BMI, non-European and Asian origin was associated with the development of diabetes after GDM in a multivariate logistic regression analysis, whereas Arab origin was not. Our results highlight the importance of preventive measures to ensure a healthy lifestyle in women with GDM, particularly in high-risk ethnic groups.