The combined oral contraceptive pill may reduce the risk of type 2 diabetes mellitus (T2DM) in women with polycystic ovary syndrome (PCOS) by more than a quarter, a study published in Diabetes Care has found.
The authors said the study presents a potential treatment option for dysglycaemia — defined as pre-diabetes and T2DM — in patients with PCOS for “the very first time”.
Researchers at the University of Birmingham carried out a retrospective population-based cohort study, using a large UK primary care database to determine the risk of dysglycaemia in 64,051 women with PCOS and 123,545 matched controls.
After adjusting for age, social deprivation, body mass index (BMI), ethnicity and smoking, the researchers estimated that women with PCOS have twice the risk of dysglycaemia (adjusted hazard ratio 1.87, 95% confidence interval [CI] 1.78-1.97, P< 0.001) compared to those without.
Using the same database, they then carried out a nested pharmacoepidemiological case-control study of 2,407 women with PCOS and a diagnosis of dysglycaemia, and the same number of women with PCOS without a dysglycaemia diagnosis, to investigate the use of the combined oral contraceptive pill in relation to dysglycaemia risk.
The researchers found that women with PCOS who used the combined oral contraceptive pill had a 26% lower risk of dysglycaemia, across all BMI subgroups (aOR 0.74, 95% CI 0.65-0.85).
Their finding of an increased risk of T2DM in women with PCOS was consistent with results from other, smaller, studies, the researchers said.
“We knew from previous, smaller studies, that women with PCOS have an increased risk of T2DM,” said co-senior author Wiebke Arlt, director of the Institute of Metabolism and Systems Research at the University of Birmingham.
“However, what is important about our research is that we have been able to provide new evidence from a very large population-based study to show, for the very first time, that we have a potential treatment option — combined oral contraceptives — to prevent this very serious health risk.”
Krish Nirantharakumar, professor in Health Data Science and Public Health at the Institute of Applied Health Research at the University of Birmingham, and also co-senior author of the study, said that, importantly, the data highlighted that “normal weight” women with PCOS were also at increased risk of T2DM and pre-diabetes.
“This parallels our previous finding of increased NAFLD [non-alcoholic fatty liver disease] risk in normal-weight women with PCOS, further challenging the notion that PCOS-related metabolic complications are only relevant in the context of obesity. These data suggest that, rather than obesity in isolation, PCOS-specific factors, including androgen excess, underpin the increased metabolic risk.”
However, the authors said that to definitively establish causality, a large-scale randomised trial evaluating the efficacy of combined oral contraceptives in reducing the risk of dysglycemia in women with PCOS would be required, with careful comparison of the potential additional benefit of combined oral contraceptives containing antiandrogenic progestin components.