Obesity at age 20 linked to increased risk of postpartum diabetes, study finds

Obesity at the age of 20 may independently predict the development of postpartum impaired glucose tolerance (IGT) and diabetes in women with a history of gestational diabetes mellitus (GDM), according to new research published in Diabetes Research and Clinical Practice.

The study also found that losing weight before taking a 75-gram oral glucose tolerance test (OGTT) after childbirth was a protective factor against both impaired glucose tolerance and diabetes.

Researchers investigated Japanese women with a history of GDM to determine whether obesity at age 20 and weight gain from that age to pregnancy were associated with an increased risk of postpartum glucose intolerance and insulin resistance.

“We found that obesity at age 20 was an independent predictor for the onset of postpartum IGT and diabetes in women with a history of GDM,” the authors wrote. “GDM is thought to result from impaired glucose tolerance caused by pancreatic β-cell dysfunction in the context of chronic insulin resistance.”

Gestational diabetes is a form of glucose intolerance that develops during pregnancy and poses both short and long-term health risks for mother and child. It is relatively common, affecting around seven per cent of pregnancies in the United States, with approximately 86 per cent of those cases being GDM.

Risk factors for GDM include higher body weight, low physical activity, having a first-degree relative with diabetes, certain ethnic backgrounds such as African American, Latino, Native American, Asian American and Pacific Islander, hypertension and abnormal oral glucose tests. However, postpartum screening rates remain low, with only around 30 per cent of women attending follow-up testing, according to previous research published in the European Journal of Obstetrics and Gynecology and Reproductive Biology.

In the current study, participants were women with a history of GDM who had achieved good glycaemic control during pregnancy between April 2021 and March 2025. Each underwent a 75-gram OGTT twelve weeks after giving birth. They also received nutritional counselling during their first visit and were monitored every one to three weeks.

Of approximately 800 registered patients, 467 completed the OGTT at 6 to 12 weeks post-delivery. A total of 433 were included in the final analysis. The mean age was 33.4 years, and the median gestational age at GDM diagnosis was 15 weeks. Around 13.2 per cent had a previous history of GDM and just over half, 50.8 per cent, had a family history of diabetes. Nearly 45 per cent underwent hospital-based education, and 64.7 point per cent required insulin therapy.

On average, the postpartum OGTT was conducted nine weeks after delivery. Results showed that 34.2 per cent of women developed impaired glucose tolerance, while 1.8 per cent developed diabetes. Among women with normal glucose tolerance (64 per cent), the mean body mass index (BMI) at age 20 was 20.6 kg/m², compared with 21.3 kg/m² in those who developed diabetes. Rates of obesity at age 20 were 4.7 per cent and 12.2 per cent, respectively.

Obesity at age 20 was found to be an independent predictor for postpartum IGT and diabetes (adjusted relative risk: 1.726; 95 per cent confidence interval: 1.217–2.446). However, weight loss between delivery and the postpartum OGTT was identified as a protective factor against both conditions.

“We identified weight loss from delivery to the date of the postpartum 75-gram OGTT as an independent preventive factor for the onset of postpartum IGT and diabetes in women with a history of GDM,” the researchers noted. “Therefore, in these women, greater weight loss during the postpartum period may reduce the risk of developing glucose intolerance and diabetes.”