Conversion of gestational diabetes mellitus to future Type 2 diabetes mellitus and the predictive value of HbA1c in an Indian cohort

AimTo investigate the distribution of and risk factors for dysglycaemia (Type 2 diabetes and prediabetes) in women with previous gestational diabetes mellitus in India. MethodsAll women (n = 989) from two obstetric units in New Delhi and Hyderabad with a history of gestational diabetes were invited to participate, of whom 366 (37%) agreed. Sociodemographic, medical and anthropometric data were collected and 75-g oral glucose tolerance test were carried out. ResultsWithin 5 years (median 14 months) of the pregnancy in which they were diagnosed with gestational diabetes, 263 (72%) women were dysglycaemic, including 119 (32%) and 144 (40%) with Type 2 diabetes and prediabetes, respectively. A higher BMI [odds ratio 1.16 per 1-kg/m(2) greater BMI (95% CI 1.10, 1.28)], presence of acanthosis nigricans [odds ratio 3.10, 95% CI (1.64, 5.87)], postpartum screening interval [odds ratio 1.02 per 1 month greater screening interval 95% CI (1.01, 1.04)] and age [odds ratio 1.10 per 1-year older age 95% CI (1.04, 1.16)] had a higher likelihood of having dysglycaemia. The American Diabetes Association-recommended threshold HbA(1c) value of 48 mmol/mol (6.5%) had a sensitivity and specificity of 81.4 and 90.7%, respectively, for determining the presence of Type 2 diabetes postpartum. ConclusionThe high post-pregnancy conversion rates of gestational diabetes to diabetes reported in the present study reinforce the need for mandatory postpartum screening and identification of strategies for preventing progression to Type 2 diabetes. Use of the American Diabetes Association-recommended HbA(1c) threshold for diabetes may lead to significant under-diagnosis. What's new? This study provides new information pertaining to the risk of developing Type 2 diabetes among Indian women with a history of gestational diabetes mellitus. Within 5 years of a gestational diabetes pregnancy, 32% women have progressed to Type 2 diabetes. Another 40% have prediabetes. The prevalence of Type 2 diabetes rose from < 25% within 2 years to almost 50% after 2-4 years' follow-up. The utility of HbA(1c) in postpartum screening has been evaluated for the first time from an Indian sample. HbA(1c) 48 mmol/mol (6.5%) had a sensitivity and specificity of 81 and 91%, respectively, for determining the presence of Type 2 diabetes postpartum. A detailed analysis of factors associated with increased risk of dysglycaemia is provided.