Obesity may play a role in the menstrual irregularities and lower rates of fertility seen in young women with type 1 diabetes, Australian researchers say.

The role of oestrogen deficiency and PCOS in menstrual and reproductive problems was investigated in 23,752 women aged 18-39 by researchers from Monash University in Victoria as part of the Australian Longitudinal Study in Women’s Health (ALSWH).

Of the 162 women with type 1 diabetes 24% were obese compared with 16% of women without diabetes.

Menstrual irregularities were significantly more frequent in women with type 1 diabetes, compared with those without the disease (47.2% vs. 34.6%). Likewise polycystic ovarian syndrome (PCOS) was significantly increased in women with T1D, compared with those in the matched control group (14.2% vs. 5.2%).

T1D, PCOS, thyroid dysfunction, younger age, increased BMI and hypertension were independently associated with menstrual irregularity, after adjustment.

Women with T1D experienced significantly more miscarriages (45.9% vs 32.7%) and stillbirths (6.6% vs. 1.4%), despite no difference in pregnancy rates.

“Women with type 1 diabetes remain at risk of significant reproductive problems despite improvements in current therapies, and this may be partly explained by the high prevalence of obesity in this group,” concluded lead researcher Dr Eleanor Thong of the Monash Centre for Health Research and Implementation in Clayton, Australia.

The higher rates of PCOS and higher levels of androgens would also be expected to be associated with menstrual irregularities and reproductive problems, they added

Presenting the results at the Endocrine Society’s annual meeting in New Orleans, the researchers said it was also notable that one in four women with T1D were current smokers, compared to one in six women in the control group.

“Increased BMI may play a role in the development of PCOS, menstrual and reproductive problems. Furthermore, smoking is associated with an increased risk of menstrual disorders and miscarriage in this cohort,” said co-author Professor Helena Teede of the Monash Centre for Health Research and Implementation.

Further evaluation of the aetiology of menstrual irregularity in this group, particularly distinguishing between oestrogen deficiency and PCOS, is necessary to guide management, they suggested.

“Pre-conception care and counselling in reproductive-aged women with type 1 diabetes, including weight management and smoking cessation, is imperative to minimise complications in pregnancy,” they concluded.