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Polycystic ovary disease and type 2 diabetes: exploring the links

By Jane Lewis
A nationwide Danish population study of women with polycystic ovary syndrome (PCOS) has found that women with PCOS not only have a fourfold increased risk of developing type 2 diabetes, but also tend to be diagnosed with type 2 diabetes at a younger age, compared with women without PCOS. 

Published in the Journal of Clinical Endocrinology and Metabolism, it is the first nationwide study to describe the prospective risk of type 2 diabetes in patients with PCOS and the modifying effect of several risk factors, claim the study’s authors.

‘This is a large, well-conducted study, with the advantage of being a prospective design,’ Professor Bronwyn Stuckey, endocrinologist at Sir Charles Gairdner Hospital and Medical Director of the Keogh Institute for Medical Research in Perth, told Endocrinology Today.

The study included all premenopausal Danish women diagnosed with PCOS identified by the national patient register (n = 18,477), a local subgroup of women with PCOS (n = 1162) and three age-matched controls for each patient (n = 54,680). Over a median follow up of 11.1 years, the risk for developing type 2 diabetes was significantly higher in women with PCOS compared with controls (hazard ratio, 4.0), and among women with PCOS, there was a significantly higher total event rate of type 2 diabetes (8.0 per 1000 vs 2.0 per 1000 patient-years). On average, the age at diagnosis of type 2 diabetes was 31 years in women with PCOS, compared with 35 years in controls. 

Analysis of data showed a positive association between the development of type 2 diabetes in women with PCOS and several factors, most notably body mass index (BMI) and fasting blood glucose. Although increasing age was positively associated with type 2 diabetes development in women with PCOS, the association became nonsignificant after correcting for BMI, and the authors suggested it should not be included as an isolated risk marker in future guidelines, with most cases of type 2 diabetes diagnosed in women with PCOS before the age of 40 years. Use of oral contraceptives was not associated with increased risk of type 2 diabetes when gestational diabetes was not part of the diabetes outcome.

‘The PCOS population in this study was relatively lean (40% had a BMI less than 25 kg/m2) compared with most Australian and US cohorts,’ noted Professor Stuckey. ‘Nevertheless, women with PCOS had four times the rate of diagnosis of type 2 diabetes compared with controls, and an earlier age at diagnosis.’

‘This study highlights the importance of a proper assessment of glucose metabolism with an oral glucose tolerance test in women of whatever age presenting with PCOS. It also emphasises the importance of preventing weight gain.’ 

‘Previous research in our group, cited in this paper, looked at this from the opposite perspective, PCOS in women with type 2 diabetes, and found very similar results,’ she added.
J Clin Endocrinol Metab 2017; 102: 3848-3857.

Picture credit: © Gustoimages/SPL