Furthermore, gestational diabetes (GD) is associated with a nearly 13 times increased risk of developing postpartum diabetes, according to an analysis of health information from more than one million women who delivered babies in Ontario, Canada, from April 1994 to March 2008.
The investigators, who reported their findings in PLOS Medicine (2013;10:e1001425), were surprised at the magnitude of increased risk for diabetes conferred by these conditions. They recommend that health care providers screen their pregnant patients for a history of preeclampsia or gestational hypertension.
“Also, they should screen their female patients regularly for diabetes, and counsel them to maintain a normal weight and exercise regularly because this may prevent the onset of diabetes,” lead investigator Denice Feig, MSc, told Renal & Urology News.
Dr. Feig is a scientist with the Institute for Clinical Evaluative Sciences in Toronto, and the head of the Mount Sinai Hospital’s Diabetes & Endocrinology in Pregnancy Program. Her team conducted the study because previous research showed women with PEC and GH also have insulin resistance, and PEC/GH is associated with other disorders linked to intrapartum insulin resistance.
The team identified women with PEC, GH or GD from the Canadian Institute for Health Information Discharge Abstract Database and excluded those with pre-existing diabetes or hypertension. They analyzed the resulting 1,010,068 women’s records.
The available information did not include obesity level or other factors known to be associated with the development of diabetes such as family history and amount of physical activity. It also did not indicate whether the cases of postpartum diabetes were type 1 or type 2; however, the investigators believe most cases were likely to be type 2 because of the age of the women in the study.
The number of women who would have to be followed for five years to detect one case of diabetes was 4,511 with GH alone, 123 for PEC alone, 68 for GD alone, 31 for GD plus PEC and 105 for GD plus GH.
The 30,852 women with GD were significantly older than those without this condition, and also had lower incomes. Moreover, they were more likely to have pre-existing hypertension and comorbidities.
The researchers performed a multivariate analysis that involved adjustment for age, income quintile, pre-existing hypertension, and comorbidities. This revealed that PEC alone and GH alone are associated with a twofold higher risk of developing diabetes. GD alone is associated with a 12.8 times increased risk. GD plus PEC is associated with a 15.7 times increased risk and GD plus GH are associated with an 18.5 times increased risk.
The highest risk was found in women with GD, PEC, and preterm delivery: their risk was 30.7 times greater than that of pregnant women without GD, GH or PEC.
Adjustment for parity strengthened these associations further. For example, the risk of developing diabetes was increased 16.6-fold in women with GD alone, 22.5-fold for women with GD plus PEC, and 23.5-fold for GD plus GH.
The study also showed that among women with GH plus PEC the risk for developing diabetes was stable out to the median follow-up time of 8.5 years. Those with GD alone or together with GH or PEC had a decreased risk over time of developing diabetes after pregnancy compared with pregnant women without GH, PEC or GD. The latter finding may be due to early development of diabetes among those who are at the highest risk, Dr. Feig’s team hypothesized, noting this is consistent with the natural history of postpartum diabetes.