Gestational diabetes ups long-term risk of impaired glucose tolerance, type 2 diabetes

In women with a history of gestational diabetes, type 2 diabetes and impairments in glucose tolerance are likely to develop in the long-term, reports a new study.

Researchers conducted a prospective nested case-cohort study that included 118 women (mean age, 50.3 years) who were followed for 8, 15 and 22 years. Oral glucose tolerance tests and insulin assays were performed during follow-up assessments. The risk of impaired glucose tolerance or type 2 diabetes was the main outcome.

Over a mean follow-up of 22.5 years, 20 cases of type 2 diabetes were detected, with an overall incidence rate of 16.9 percent. At all time points, median plasma glucose levels were significantly higher in women with a history of gestational diabetes mellitus (GDM; p=0.001) or gestational impaired glucose tolerance (GIGT; p<0.001) than their comparators with normal glucose tolerance.

This was confirmed by multiple logistic regression analysis. A history of GDM/GIGT was significantly predictive of the development of type 2 diabetes or abnormal glucose tolerance at follow-up (odds ratio [OR], 2.78, 95 percent confidence interval [CI], 1.18–6.55; p=0.02).

The researchers also assessed the effect of GDM on longitudinal changes in glucose tolerance. By 8 years after birth, 40.3 percent of women with GDM/GIGT history were dysglycaemic, as compared to only 17.7 percent of those who had normal glucose tolerance (p=0.001). The corresponding values at 15 years were 51.1 percent and 20.2 percent (p<0.001), and 52.6 percent and 30.0 percent (p=0.025) at 22 years.