Second Pregnancy Gestational Diabetes Tied to Future Type 2 Diabetes Risk

Gestational diabetes during only the second vs only the first pregnancy is associated with a higher risk for future incident type 2 diabetes, according to study findings published in JAMA Network Open.

Earlier study findings have established a relationship between gestational diabetes and type 2 diabetes. However, the association between incident type 2 diabetes risk and the order of gestational diabetes occurrences remains unclear.

To compare the risk for incident type 2 diabetes between patients who had gestational diabetes during their first pregnancy only vs second pregnancy only, researchers conducted a retrospective cohort study by acquiring data from the Quebec Statistical Institute. Patients had 2 or more consecutive singleton deliveries from April 1990 through December 2012.

The primary outcome was incident diabetes. The researchers stratified patients according to gestational diabetes presence during: (1) only first pregnancy; (2) only the second pregnancy; (3) both pregnancies; and, (4) no pregnancies.

The study included a total of 431,980 patients (mean [SD] age, 30.1 [4.5] years) who presented with an average of 2.8 years (SD, 1.5) between deliveries. Among all patients, 87.3% were from America, Australia, or Europe; 1.9% were from Africa or the Caribbean; 3.7% were from Arab-speaking regions; 3.0% were from Asia; and 4.0% were from an unlisted region.

The 4 exposure groups had distributions of: 2.5% (gestational diabetes, first pregnancy only); 3.7% (gestational diabetes, second pregnancy only); 1.9% (gestational diabetes, both pregnancies); and, 91.1% (no gestational diabetes). After a median of 11.5 years, all exposure groups demonstrated increased incidence of type 2 diabetes, with incident ratios of:

• 1.4 per 1000 person-years (no gestational diabetes);
• 6.7 per 1000 person-years (gestational diabetes, first pregnancy only);
• 12.4 per 1000 person-years (gestational diabetes, second pregnancy only); and,
• 25.5 per 1000 person-years (gestational diabetes, both pregnancies).

In adjusted analyses, the researchers identified observed increased risks for incident type 2 diabetes — relative to patients without gestational diabetes — among patients with gestational diabetes during:

• First pregnancy only (hazard ratio [HR], 4.35; 95% CI, 4.06-4.67);
• Second pregnancy only (HR, 7.68; 95% CI, 7.31-8.07); and,
• Both pregnancies (HR, 15.80; 95% CI, 15.00-16.61).

Type 2 diabetes risk was higher among patients with gestational diabetes during the second pregnancy only (HR, 1.76; 95% CI, 1.63-1.91) and both pregnancies (HR, 3.63; 95% CI, 3.36-3.93) compared with the first pregnancy only.

Adjustments for obesity slightly attenuated type 2 diabetes risk, which remained elevated among all exposure groups relative to the control group.  

The researchers also identified higher risks for type 2 diabetes among all other ethnocultural backgrounds compared with European.

“[A]mong women with 2 consecutive singleton pregnancies, without diabetes before or between pregnancies, the absence of [gestational diabetes] in a second pregnancy following [gestational diabetes] in the first suggests that the mother is taking effective diabetes prevention measures,” the researchers concluded. “If confirmed, she should be encouraged to continue.”

This article originally appeared on Endocrinology Advisor