In this community-based prospective cohort study, we found that both gestational diabetes and gestational impaired glucose tolerance were associated with an adverse metabolic profile at 3 years postpartum, independent of body mass index and parental history of diabetes.
Strengths of our study include its prospective assessment of gestational glucose tolerance and standardized assessment of three-year outcomes. Nevertheless, our results must be interpreted within the context of the study design. Our population was healthy, resulting in low rates of gestational diabetes and impaired glucose tolerance. Among the 91 women ages 30–39 for whom we had data on waist circumference, blood pressure, serum lipids and glucose, only 5 (5.5%, 95% CI 1.8–12.4%) met criteria for the metabolic syndrome, compared with 15% of women in this age range in the general US population(21
). In addition, the number of participants with fasting blood samples limited power to detect subtle differences among glucose tolerance groups, and we were not able to define metabolic syndrome in the full cohort. Further studies in larger populations will be needed to validate our findings. Nevertheless, our study size is comparable to several other studies that have assessed metabolic markers among postpartum women with a history of GDM(2
). We did not measure post-glucose load insulin or glucose in our population, and therefore we were unable to compare indices of glycemia, insulin sensitivity and beta-cell function. Nevertheless, our study included postpartum measures of adiponectin, which is highly correlated with beta cell dysfunction during pregnancy(23
) and with 2-h post OGTT in the postpartum period(24
Our results confirm and extend earlier work linking gestational glucose tolerance with an adverse maternal metabolic profile in later life. Several authors have reported an increased risk of impaired glucose tolerance and type 2 diabetes among women with abnormal glucose screening results in pregnancy in the setting of both normal OGTT(7
) and one abnormal GTT result (5
). Moreover, both IGT and GDM have been associated with the metabolic syndrome at 3 months postpartum(8
). Other authors have reported associations between GDM and markers of metabolic dysfunction after pregnancy. At a mean of 2 years postpartum, Costacou et al reported adverse associations between history of GDM (N=22) and waist circumference, hemoglobin A1c, and HOMA-IR, compared with women without a history of pregnancy complications (N=29)(22
). Heitritter et al similarly compared women with a GDM history (N=23) with normal controls (N=23) at a mean of 4 years postpartum. Women in the GDM group had higher diastolic blood pressure, mean arterial pressure, heart rate, fasting glucose, HOMA, triglycerides, CRP, IL-6, and PAI-1 and lower adiponectin than women in the control group.
No studies to our knowledge have measured associations between IGT and LDL, inflammatory markers or adipokines, or with other metabolic markers beyond 3 months postpartum. We found that women with impaired glucose tolerance during pregnancy had elevations of triglycerides, hemoglobin A1c and CRP, as well as lower HDL, after adjustment for current body mass index and parental history of diabetes. Women with a history of GDM had triglyceride and HDL levels that were similar to those with IGT, but they had higher HOMA-IR and waist circumference, as well as lower adiponectin levels.
These adverse profiles of intermediate markers among women with pregnancy dysglycemia imply increased risk for cardiovascular disease, which is consistent with findings in a recent population-based cohort study (3
). In that study, compared with women who did not undergo glucose tolerance testing during pregnancy and therefore were presumed to have had normal glucose screening test results, women with both IGT and GDM were more likely to experience cardiovascular events (IGT OR 1.19, 95% CI 1.02–1.39; GDM OR 1.66, 95% CI 1.30–2.13).
Compared with women with normal glucose testing during pregnancy, we found that women with a history of gestational glucose intolerance had unfavorable markers of glucose and lipid homeostasis and inflammation. These findings persisted with adjustment for current body mass index, suggesting that normal or overweight women with a history of IGT may be at risk for metabolic dysfunction at 3 years postpartum. These women may therefore benefit from dietary changes, physical activity, and/or screening for metabolic syndrome. Current guidelines recommend screening women with a history of GDM for type 2 diabetes(26
In conclusion, in a prospective study of maternal and infant health, we found that maternal gestational glucose intolerance and gestational diabetes were both associated with adverse metabolic profile at 3 years postpartum, independent of other clinical risk factors.