Prepregnancy Overweight and Gestational Diabetes as Determinants of Subsequent Diabetes and Hypertension After 20-Year Follow-Up

Abstract

The prevalence of overweight or obesity and gestational diabetes mellitus (GDM) is increasing and is a major public health concern. Maternal risk factors for development of diabetes in later life include GDM and overweight during pregnancy. Overweight is a strong risk factor for GDM, and the occurrence of both increases the risk for subsequent metabolic syndrome. Little data are available on the risk of diabetes and metabolic diseases in women with normal glucose tolerance during pregnancy, who have risk factors for GDM. Moreover, few studies have investigated the individual contribution of overweight and GDM during pregnancy to the risk of diabetes and hypertension in later life. This prospective population-based study evaluated prepregnancy overweight and GDM as determinants of risk for diabetes and hypertension, separately and in combination, 20 years after pregnancy. Population-based cohort data from the Northern Finland Birth Cohort 1986 were linked with register-based data on diagnosis of diabetes and hypertension obtained from records on reimbursement of medical expenses and diagnoses at hospital discharge. The oral glucose tolerance test (OGTT) was used to diagnose GDM. Several categories of risk were evaluated for diabetes and hypertension (which were the primary study outcomes). These included: (1) normal weight women with GDM (n = 70); (2) overweight women with GDM (n = 54); (3) normal-weight (n = 768); (4) overweight (n = 250) women with risk factors for GDM but normal OGTT results; and (5) women with no risk factors for GDM (n = 5341). Calculation of the population-attributable fractions (PAFs) estimated the cumulative incidence of diabetes and hypertension associated with prepregnancy overweight. Analysis of time-to-event curves showed that the cumulative incidence of diabetes and hypertension diagnosed in the whole study population was 1.3% and 7.5%, respectively. Women with concomitant prepregnancy overweight and GDM were at extremely high risk of diabetes (hazard ratio [HR], 47.24; PAF, 15.8%) and hypertension (HR, 9.16; PAF, 4.4%). The occurrence of prepregnancy overweight in women with a normal OGTT during pregnancy was associated with increased risk of diabetes (HR, 12.63; PAF, 22.2%) and hypertension (HR, 2.86; PAF, 6.0%), whereas a finding of GDM only among women with prepregnancy normal weight was associated with increased risk of diabetes (HR, 10.61; PAF, 5.2%) but not hypertension. These findings show that prepregnancy overweight is a critical risk factor for development of diabetes and hypertension 20 years after delivery. Overweight combined with even mild GDM markedly increases the risks of these diseases.