Endocrine Abstracts

Gestational diabetes mellitus (GDM) is a common condition affecting 2–10% of pregnant women in the USA and in Europe and is associated with adverse outcomes for both the fetus and the mother. Previous GDM is a major risk factor for type 2 diabetes (T2DM), which occurs in 20–60% of affected women within 5 years of the pregnancy¹. In studies comparing women with GDM with those with unaffected pregnancies, relative risks for the development of diabetes after pregnancy range from 3 to 20. In a large Canadian study² of 21 823 women with a previous GDM, the probability of diabetes developing after gestational diabetes was only 3.7% at 9 months, but 18.9% at 9 years after delivery.

Women with a history of GDM are also at increased risk of other cardiovascular risk factors^3,4, such as obesity, hypertension, dyslipidemia, and the metabolic syndrome, as well as subclinical atherosclerosis. In a population-based retrospective cohort study⁵ from Ontario-Canada 8191 women with GDM and 81 262 women without GDM were followed-up for a median of 11.5 years. Diabetes developed during follow-up in 2214 (27.0%) of the women with GDM and 2596 (3.2%) of the women without GDM. The hazard ratio for cardiovascular disease (CVD) events was 1.71, but after adjustment for subsequent T2DM, the hazard ratio was attenuated to 1.13. Thus, young women with GDM have a substantially increased risk for CVD compared with women without GDM, however much of this increased risk is attributable to subsequent development of T2DM. These findings are in line with a cross-sectional study, which reported that women with a history of GDM had odds ratios for CVD and coronary artery disease of 1.85 and 1.58⁶.

Clinical trials now provide strong evidence for the impact of multiple interventions to prevent the progression to T2DM in women with a history of GDM. Both lifestyle modification and pharmacological therapies (metformin and pioglitazone) have been shown to reduce diabetes development by 50% or more. The diagnosis of GDM should initiate a long-term intervention and diagnostic process to minimize the risk of developing diabetes and CVD as early in the course of disease as possible.

References: 1. England LJ et al. Am J Obstet Gynecol 2009 200 365.e1–365.e8.

2. Feig DE et al. CMAJ 2008 179 229–234.

3. Krzyzanowska K et al. Diabetologia 2008 51 1115–1122.

4. Kautzky-Willer et al. JCEM 2008 93 1689–1695.

5. Shah BR et al. Diabetes Care 2008 31 1668–1669.

6. Carr DB et al. Diabetes Care 2006 29 2078–2083.