Aim: To assess the glucose tolerance of South Asian and Caucasian women with previous gestational diabetes mellitus (GDM).
Method: A retrospective follow-up study of 189 women diagnosed with GDM between 1995 and 2001. Glucose tolerance was reassessed by oral glucose tolerance test at a mean duration since pregnancy of 4.38 years.
Results: South Asian women comprised 65% of the GDM population. Diabetes developed in 36.9% of the population, affecting more South Asian (48.6%) than Caucasian women (25.0%). Women developing diabetes were older at follow-up (mean (SD) 38.8 (5.7) vs 35.9 (5.6) years; p<0.05) and had been heavier (body mass index 31.4 (6.3) vs 27.7 (6.7) kg/m(2); p<0.05), more hyperglycaemic (Gl(0) 6.5 (1.7) vs 5.2 (1.1) mmol/l; p<0.01: G(120) 11.4 (3.3) vs 9.6 (1.8) mmol/l; p<0.01: HbA1c 6.4 (1.0) vs 5.6 (0.7); p<0.01) and more likely to require insulin during pregnancy (88.1% vs 34.0%; p<0.01). Future diabetes was associated with and predicted by HbA1c taken at GDM diagnosis in both South Asian (odds ratio 4.09, 95% confidence interval 1.35 to 12.40; p<0.05) and Caucasian women (OR 9.15, 95% CI 1.91 to 43.87; p<0.01) as well as by previously reported risk factors of increasing age at follow-up, pregnancy weight, increasing hyperglycaemia and insulin requirement during pregnancy.
Conclusion: GDM represents a significant risk factor for future DM development regardless of ethnicity. Glycated haemoglobin values at GDM diagnosis have value in predicting future diabetes mellitus.