January 10, 2020
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Gestational diabetes may heighten type 2 diabetes risk decades after pregnancy

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Ronald C.W. Ma

Type 2 diabetes risk may be higher even after more than 20 years for Chinese women who develop gestational diabetes compared with those who do not, according to findings published in the Journal of Diabetes Investigation.

“The risk for conversion to manifest type 2 diabetes in women with a history of gestational diabetes is well known,” Ronald C.W. Ma, MD, professor and head of the division of endocrinology and diabetes in the department of medicine and therapeutics at the Chinese University of Hong Kong, and colleagues wrote. “However, the natural history of these patients has rarely been examined beyond 10 years following pregnancy.”

Ma and colleagues assessed type 2 diabetes and metabolic syndrome development among 118 women (mean age, 50.3 years) during 22 years of follow-up after pregnancy. Gestational diabetes was diagnosed at the time of pregnancy using an oral glucose tolerance test at 24 to 28 weeks and according to WHO 1999 diagnostic criteria. There were four women who had gestational diabetes; 34 women who had gestational impaired glucose tolerance, and 80 women who had normal glucose tolerance. The researchers also assessed fasting plasma glucose, 2-hour glucose via an oral glucose tolerance test, insulin resistance, beta-cell function, height and weight at 8, 15 and 22 years.

The researchers found that type 2 diabetes and abnormal glucose tolerance were more than twice as likely to develop among those who had gestational diabetes or gestational impaired glucose tolerance compared with those who had normal glucose tolerance (OR = 2.78; 95% CI, 1.18-6.55).

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Type 2 diabetes risk may be higher even after more than 20 years for Chinese women who develop gestational diabetes compared with those who do not.

Type 2 diabetes was present in more women with gestational diabetes or gestational impaired glucose tolerance at 22 years (52.6%) than in those with normal glucose tolerance (30%; P = .025), according to the researchers, who noted type 2 diabetes was present in more women with gestational diabetes or gestational impaired glucose tolerance at 8 years (40.3% vs. 17.7%; P = .001) and 15 years (51.1% vs. 20.2%; P < .001) as well.

Women with gestational diabetes had higher 2-hr glucose of 8.09 mmol/L at 8 years compared with women with normal glucose tolerance (6.33 mmol/L; P = .003). At 15 years, women with gestational diabetes or gestational impaired glucose tolerance had higher fasting glucose of 5.33 mmol/L compared with 4.85 mmol/L in women with normal glucose tolerance (P = .001), and higher 2-hour glucose (7.76mmol/l) compared with women with normal glucose tolerance (6.42mmol/l, p=0.013). Women with gestational diabetes had a mean 2-hour glucose level of 7.76 mmol/L at 15 years and 8.69 mmol/L at 22 years, whereas women with normal glucose tolerance averaged 6.42 mmol/L (P = .013) and 6.81 mmol/L (P = .005) at each respective time point.

“These reports indicate a high proportion of gestational diabetes-positive women develop dysglycemia in the postpartum period, yet interestingly, roughly half do remain [at] normal glucose tolerance more than 20 years postpartum,” the researchers wrote. “Taken together, the observation that roughly half of the gestational diabetes women had abnormal glucose tolerance or type 2 diabetes at follow-up strongly indicate[s] that any level of dysglycemia during mid-pregnancy OGTT imparts a substantial risk for subsequent abnormal glucose tolerance or type 2 diabetes in middle age.”

In addition, the researchers found that metabolic syndrome was more than five times as likely to develop among women who had a BMI of at least 23 kg/m2 before pregnancy compared with a lower BMI (OR = 5.42; 95% CI, 1.87-15.72).

“The presence of gestational diabetes or gestational impaired glucose tolerance was not predicative of metabolic syndrome at follow-up, although BMI ≥ 23 kg/m2 at booking was highly predictive of future metabolic syndrome after adjustment for covariates,” the researchers wrote. “Clearly, a high BMI at booking is a more significant driver of cardiometabolic risk as compared to high glucose.” – by Phil Neuffer

Disclosures: Ma reports he has received honoraria, travel support and research and educational grants for his institution from AstraZeneca, Bayer, Boehringer Ingelheim, Merck Sharp & Dohme, Pfizer and Worldwide Diabetes.