Diabetes and abnormal glucose tolerance in women with previous gestational diabetes

OBJECTIVE - In Spanish women with gestational diabetes mellitus (GDM), we aimed to study the progression to diabetes and abnormal glucose tolerance (AGT) and identify predictive factors. RESEARCH DESIGN AND METHODS - In 696 women with GDM and 70 control women, glucose tolerance was evaluated postpartum and at 5-year intervals. RESULTS - In the GDM group, the cumulative risk for diabetes and AGT was 13.8 and 42.4% after 11 years compared with 0 and 2.8% in control women, respectively (P < 0.05). Independent predictive factors for diabetes were previous hyperglycemia, four abnormal glucose values on the diagnostic oral glucose tolerance test (OGTT) or overt diabetes during pregnancy, 2-h blood glucose on the diagnostic OGTT ≥ 11.7 mmol/l, gestational age at diagnosis <24 weeks, and prepregnancy BMI ≥ 26.4 kg/m2. All of these factors (some with different cutoff points) in addition to fasting glycemia were predictors of AGT also. The risk was nonlinear. Four abnormal glucose values on the diagnostic OGTT or overt diabetes during pregnancy was the strongest predictive factor for diabetes (relative risk 3.92), and prepregnancy BMI was the predictive factor with the highest attributable fraction in the whole group (13.3%). When first postpartum OGTT data were included in the analysis, predictors changed, but the overall prediction was similar. CONCLUSIONS - Spanish women with GDM have an increased risk of diabetes and AGT. Predictive factors display a nonlinear relationship. The strongest predictive factor for diabetes was four abnormal glucose values on the diagnostic OGTT or overt diabetes during pregnancy; the factor with the highest attributable fraction in the whole group was prepregnancy BMI.