Gestational DM not only increases risk of T2DM, but also of hypertension and IHD
Increased risk of ischemic heart disease, hypertension, and type 2 diabetes in women with previous gestational diabetes mellitus, a target group in general practice for preventive interventions: A population-based cohort studyDaly B, Toulis KA, Thomas N et al., - PLoS Medicine. Published: January 16, 2018
The incidence of gestational diabetes mellitus (GDM) is on the increase, largely due to the obesity epidemic and increasing maternal age . GDM is well-known to be a predictor for progression to type 2 diabetes (T2DM), but less is known about genetic and lifestyle factors that affect whether T2DM is developed after delivery .
Three studies that evaluated the association between GDM and T2DM demonstrated an increased risk of CV events in women who had GDM as compared with those without [4-6]. Lifestyle changes can improve outcomes , and it is recommended annual screening for T2DM is done in women with GDM. No recommendations have, however, been formulated to screen, identify and actively manage CV risk factors in those women postpartum.
The current study examined the risk of CV disease in women who had GDM and it was assessed in which proportion of women with GDM CV risk assessment was performed in primary care during the first 3 years postpartum. Data of the UK Health Improvement Network (THIN) database were used for a retrospective cohort study . Women who became pregnant between 1 February 1990 and 15 May 2016, younger than 50 years old, were eligible for inclusion. Women diagnosed with GDM (n=9118, mean age at delivery: 33 years, range: 14-47) were identified and randomly matched with up to 4 pregnant control women without GDM. Primary outcomes were clinical diagnosis of coronary artery disease (ischemic heart disease: IHD) and cerebrovascular disease (stroke or transient ischemic attack: TIA). Secondary outcomes were incident hypertension and T2DM. Median follow-up was 2.9 years, range was less than 1 to 25 years.
- Women diagnosed with GDM were over 20 times more likely to develop T2DM (Incidence rates ratio: IRR=21.96, 95%CI: 18.31-26.34, P<0.001). Risk of developing hypertension was almost two-fold increased (IRR: 1.85, 95%CI: 1.59-2.16, P<0.001), after adjusting for age, Townsend quintile/socio-economic status, BMI and smoking.
- After further correction for baseline lipid-lowering medication and hypertension, women with GDM showed a higher risk of developing IHD (IRR: 2.78, 95%CI: 1.37-5.66, P=0.005). The risk of cerebrovascular disease was not increased (IRR: 0.95, 95%CI: 0.51-1.77).
- Not all (5/14) women with GDM who developed IHD, also developed T2DM postpartum.
- The higher cumulative incidence of T2DM, hypertension and IHD in women with GDM compared to controls persisted throughout the 25-year study period.
- Effect sizes for T2DM, hypertension, IHD and stroke or TIA were not different in sensitivity analyses that included ethnicity in the model.
- Medical records of women with GDM documented some glycemic measurement in 58% in the first year postpartum. In the second and third year following delivery, the proportion with glycemic measurement decreased to less than 40% and 24% of women.
- Surveillance for risk factors, concerning T2DM and lipid measurements, in the postpartum period was lower in control women as compared with those with GDM, up to 3 years postpartum. Assessment of hypertension and smoking in years 2 and 3 did not differ between women with GDM and controls.
This population-based study, for the first time, reports on the increased CV risk in women diagnosed with GDM. Women with GDM are over 20 times more likely to develop T2DM and have an almost doubled risk of hypertension, and 2.8-fold higher risk of IHD, compared with control women. This increased risk persists in the long run. Despite the higher risk, postpartum screening of diabetes and CV risk was poor.