The increased risk of type 2 diabetes in women with polycystic ovary syndrome is well established, but a new analysis has shown that obesity is the major mediator and a target for preventing or reversing this comorbidity.
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“Most women with PCOS are obese, complicating the effort to understand whether high rates of diabetes in this population are due to PCOS or excess weight, but our study now suggest that obesity isa targetable risk factor,” reported Panagiotis Anagnostis, MD, PhD, a reproductive endocrinologist at the Medical School of Aristotle University, Thessaloniki, Greece.
Obesity is also a known risk factor for type 2 diabetes (T2D), but there is reason to suspect that PCOS, which is associated with abnormal carbohydrate metabolism, has a direct impact on the risk of developing T2D, according to Dr. Anagnostis. It is also reasonable to expect “a synergistic deleterious effect” from PCOS and obesity on adverse changes in glucose metabolism that lead to T2D.
Even though rates of obesity among women with PCOS reach 80% in some studies, Dr. Anagnostis attempted to disentangle the relationship between obesity, PCOS, and risk of T2D using a large set of data drawn from a comprehensive search of published studies.
After screening with predefined criteria, 12 studies provided data on 224,284 women, of whom 45,361 had PCOS and 5,717 had T2D. Not least of the criteria for inclusion in this analysis, all studies stratified women as obese, defined as a body mass index (BMI) greater than 30 kg/m2, or nonobese, he reported at the annual meeting of the Endocrine Society.
Diabetes risk tripled in PCOS
When compared without regard to BMI, the relative risk of having T2D among those with PCOS relative to those without this condition was more than three times greater (RR 3.13; P < .001). When women with PCOS were stratified for BMI, obesity was associated with a more than fourfold increased risk relative to controls without PCOS (RR, 4.06; P < .001).
In women who were nonobese, the risk of T2D was numerically higher for those with PCOS than those without (RR, 2.68), but it was only a trend with a large confidence interval (95% confidence interval, 0.97-7.49).
Among women with PCOS, those who were obese also had a more than fourfold and highly significant increased risk of T2D relative to those who were not obese (RR, 4.20; P < .001).
The message from these data is that obesity is a major and potentially modifiable risk factor for diabetes in women with PCOS, according to Dr. Anagnostis.
He said these data provide the basis for recommending weight loss specifically for managing this common PCOS comorbidity.
Almost the same relative risk of diabetes was derived from an analysis of a women’s health database published 2 years ago in Diabetes Care. In that study with 1,916 person-years of follow-up, the hazard ratio for T2D was also more than three times greater (HR, 3.23; P < .001) for those with PCOS relative to those without the syndrome.
However, normal BMI did not eliminate risk of developing diabetes in this study. Rather, the relative risk of T2D in women with PCOS was higher in those of normal weight, compared with those who were obese (HR, 4.68 vs. 2.36; P < .005). The investigators recommend screening all women with PCOS at least every 3 years with more frequent screening in those with risk factors.
PCOS complexity challenges simple conclusions
The complexity of disturbed metabolic pathways in patients with PCOS and obesity might explain some of the difficulty in unraveling the relationship between these two disease states and diabetes risk. In one recent review, it was suggested that obesity and PCOS share interrelated adverse effects on glucose metabolism. As a result, these associations are “more complex than a simple cause-and-effect process.” the authors of that article concluded.
Furthermore, in their examination of metabolic pathways, genetic susceptibility, and behavioral factors that might link PCOS, weight gain, and T2D, the authors did not ignore the psychological impact of PCOS in causing obesity and, as a byproduct, diabetes. These psychological factors might be relevant to treatment.
For example, depression and stress “might hamper ongoing attempts at lifestyle change and therefore effective weight loss” in at least some women, they cautioned.
However, in encouraging weight loss in overweight women with PCOS, the debate about cause of T2D might be moot in practical terms, according to Michael Dansinger, MD, founding director of the diabetes reversal program at Tufts Medical Center, Boston.
“Reducing excess body fat reduces the risk of type 2 diabetes,” Dr. Dansinger said in an interview. “Since women with obesity and PCOS are clearly at risk for future type 2 diabetes, that’s another reason to lose excess body fat through healthy eating and exercise.”
Dr. Anagnostis and Dr. Dansinger reported no relevant conflicts of interest.