Gestational diabetes may signal health risks that extend well beyond pregnancy, according to a large U.S. study that followed more than 1 million women after delivery.
Women who had gestational diabetes were much more likely to later be diagnosed with type 2 diabetes or prediabetes and also had higher rates of high cholesterol, high blood pressure, obesity and cardiovascular disease. The study, published in JAMA Network Open, does not show that gestational diabetes caused those later conditions. Instead, researchers say it may serve as an early marker of underlying metabolic vulnerability that becomes apparent during pregnancy.
Researchers analyzed commercial insurance records for 1,153,998 women who gave birth between 2007 and 2023 and had no diagnosed cardiovascular, kidney or metabolic conditions before delivery. About 95,000, or 8.2%, had gestational diabetes. Women were followed for an average of just over three years, although some remained in the dataset for more than a decade.
The strongest difference involved blood sugar.
Women with gestational diabetes were about 10 times as likely to be diagnosed with type 2 diabetes and more than five times as likely to be diagnosed with prediabetes during follow-up compared with women who did not have gestational diabetes.
The gaps appeared relatively early after pregnancy. During years one and two after delivery, the rate of type 2 diabetes was about 11 times higher among women who had gestational diabetes. Although that difference became smaller over time, the elevated rate persisted later in follow-up.
The findings are consistent with previous research showing that gestational diabetes is strongly associated with later type 2 diabetes. But researchers wanted to look beyond blood sugar to see how several aspects of cardiovascular and metabolic health unfolded within the same group of women.
Other differences were smaller but still notable.
Gestational diabetes was associated with about twice the likelihood of a later high cholesterol diagnosis. Women who had it were also about 76% more likely to be diagnosed with high blood pressure and 75% more likely to be diagnosed with obesity.
Metabolic syndrome, a cluster of conditions that together raise the risk of health problems including heart disease and type 2 diabetes, was nearly three times as likely among women who had gestational diabetes.
Those associations generally persisted in the years after pregnancy rather than disappearing soon after delivery.
Cardiovascular disease showed a more modest association. Overall, women with gestational diabetes had about a 28% higher likelihood of a cardiovascular disease diagnosis during follow-up.
Researchers cautioned that this result was less robust than the findings for metabolic conditions. The women in the study were relatively young and the average follow-up period was only about three years, which may be too short to fully capture cardiovascular diseases that often develop over decades.
The kidney findings were less clear.
Using the study's primary definition, researchers found no significant association between gestational diabetes and chronic kidney disease. Only a small number of kidney disease cases occurred among women with gestational diabetes.
When researchers expanded the definition to include additional kidney-related conditions, an association did emerge. The authors said longer studies using laboratory measures of kidney health will be needed to understand the relationship more clearly.
Importantly, gestational diabetes may not be the starting point for these health differences.
Previous studies have found that differences in blood sugar, cholesterol and blood pressure can sometimes be present before pregnancy among women who later develop gestational diabetes. Pregnancy places additional demands on the body, which can make an underlying tendency toward insulin resistance or other metabolic problems easier to detect.
That means gestational diabetes may function partly as an early warning sign rather than independently causing the conditions diagnosed years later.
The study also cannot account for every difference between women who did and did not develop gestational diabetes.
Researchers did not have prepregnancy body mass index data and lacked complete information on factors including smoking, race and ethnicity, socioeconomic status, medications and high blood pressure disorders during pregnancy. Statistical analyses designed to estimate the effect of some missing factors reduced the size of several associations, although most of the metabolic findings remained elevated.
The research relied on insurance claims, meaning diagnoses depended partly on whether someone received medical care and was tested for a condition. Women with gestational diabetes may also undergo more blood sugar testing after pregnancy than other women, making type 2 diabetes and prediabetes more likely to be detected.
The researchers found that the elevated rates continued years later, however, suggesting that increased screening alone probably does not explain the full difference.
The study population presents another limitation. All participants had commercial insurance, which means the findings may not fully represent women with Medicaid, no insurance or unstable insurance coverage.
Taken together, the findings suggest that gestational diabetes may provide information about a woman's health well beyond the pregnancy in which it occurs. The clearest signal remains future blood sugar problems, but the study suggests the picture may extend to cholesterol, blood pressure, weight and other aspects of metabolic health.
The study received no specific external funding. Researchers accessed data through the Stanford Center for Population Health Sciences Data Core, which receives support from a National Institutes of Health award and internal Stanford funding. One author, Mindie H. Nguyen, M.D., reported research grants from several pharmaceutical and health care companies and personal fees from GSK outside the submitted work.