OBJECTIVE -To examine factors associated with variation in the risk for type 2 diabetes in women with prior gestational diabetes mellitus (GDM).RESEARCH DESIGN AND METHODS -We conducted a systematic literature review of articles published between January 1965 and August 2001, in which subjects underwent testing for GDM and then testing for type 2 diabetes after delivery. We abstracted diagnostic criteria for GDM and type 2 diabetes, cumulative incidence of type 2 diabetes, and factors that predicted incidence of type 2 diabetes.RESULTS -A total of 28 studies were examined. After the index pregnancy, the cumulative incidence of diabetes ranged from 2.6% to over 70% in studies that examined women 6 weeks postpartum to 28 years postpartum. Differences in rates of progression between ethnic groups was reduced by adjustment for various lengths of follow-up and testing rates, so that women appeared to progress to type 2 diabetes at similar rates after a diagnosis of GDM. Cumulative incidence of type 2 diabetes increased markedly in the first 5 years after delivery and appeared to plateau after 10 years. An elevated fasting glucose level during pregnancy was the risk factor most commonly associated with future risk of type 2 diabetes.CONCLUSIONS -Conversion of GDM to type 2 diabetes varies with the length of follow-up and cohort retention. Adjustment for these differences reveals rapid increases in the cumulative incidence occurring in the first 5 years after delivery for different racial groups. Targeting women with elevated fasting glucose levels during pregnancy may prove to have the greatest effect for the effort required.
Diabetes Care 25:1862-1868, 2002G estational diabetes mellitus (GDM), or impaired glucose intolerance first diagnosed during pregnancy (1), affects ϳ14% of pregnancies, or 135,000 women a year in the U.S., and is a risk factor for type 2 diabetes in the mother (2). The magnitude of the reported risk varies widely; it is unclear how much of the variation is explained by variations in ethnicity, length of follow-up, selection criteria, and tests for GDM and type 2 diabetes (3-5). Understanding the basis of differences in risk could affect screening protocols for type 2 diabetes in women with a history of GDM and identify women with GDM who may be candidates for studies of preventive interventions of type 2 diabetes.To examine the relative importance of several sources of variation on the risk of type 2 diabetes in women with GDM, we performed a systematic review of the literature, examining the cumulative incidence of type 2 diabetes in women with GDM. We examined the study design, ethnicity, criteria for diagnosis of GDM and type 2 diabetes, length of follow-up, and other predictive factors. We hypothesized that much of the difference in the risk reported among studies could be explained by different lengths of follow-up, ethnic variation, and the diagnostic criteria used.
RESEARCH DESIGN AND METHODS -We searched PubMedfor studies published from 1965 to 2001 using the search strategy "gestational ...