Objective: Menstrual cycle disorders are known to occur more frequently in patients with insulin dependent diabetes mellitus (IDDM) than in general non-diabetic population. Potential risk factors were analysed. Design: An open prospective clinical study. Methods: The cohort of 96 postmenarchal IDDM patients aged 17.8 (12-27) yr. (mean, range), menarche at 13.4 (10-14.6) yr., with IDDM onset at 9.6 (0.8-17.5) yr. and duration of IDDM 8.4 (0.1-26.2) yr. was followed up. Relation of menstrual cycle characteristics to metabolic control (HbA1C), body mass index (BMI), age at IDDM onset, duration of IDDM and to autoimmune thyroi- ditis was studied. Results: Menstrual cycle disorders were more frequent in IDDM patients (29/96, 30.2%), than in the general non-diabetic population (11-18%, p < 0.01). Secondary ammenorrhea (in 4 patients) was associated with poor IDDM control, as the level of HbA1C was significantly higher 12.6 (11.8-13.1)% than in 92 girls without ammenorrhea, 10.0 (6.1-14%) (p < 0.01). On the contrary, the effect of metabolic control or BMI was not present in 7 patients with oligomenorrhea, or in 18 patients with irregular cycle. Autoimmune thyroiditis was more frequent in patients with cycle disturbances (8/29, 27.6%), compared with those with regular cycles (8/67, 11.9%, p < 0.05). Early IDDM onset (before the age of 10) increased risk of delayed menarche (after the age of 15). Conclusions: Higher frequency of menstrual cycle disturbances in IDDM patients was confirmed. Poor metabolic control was a risk factor of secondary amenorrhea. Menstrual cycle disturbances were more frequent in patients with autoimmune thyroid disease.

        Key words: insulin dependent diabetes mellitus, IDDM, menstrual cycle, disturbances