Age at menarche in Japanese patients with type 1 diabetes mellitus: a look at changes since 1960s

Menarche is delayed in patients with type 1 diabetic mellitus (T1DM) compared to non-diabetics. The purpose of this survey study was to define the age of onset of menarche in Japanese patients with T1DM, as well the secular trends in menarcheal age across the period of 1976-2020 and determine the effects of T1DM and disease management on that age. The study subjects (n = 155) were recruited from among Japanese T1DM patients who visited the outpatient clinic of the Department of Pediatrics, Osaka City University Hospital. The study subjects experienced menarche during 1976-2020. They were divided into the menarche-post-T1DM group (n = 117) and the menarche-pre-T1DM group (n = 38), in whom menarche occurred after or before the diagnosis of T1DM, respectively. The time of birth was also stratified into five decade/time bins extending from 1960s to 2000s. The subjects filled a questionnaire on menarche. Other clinical information was obtained from the medical records. The median age at menarche was 12.5 years (11.3-13.4) (25^th-75^th percentile) for the menarche-post-T1DM group and 11.8 years (10.9-13.0) for the menarche-pre-T1DM group (p = 0.024). Menarche occurred at a significantly younger age in recent years in the menarche-post-T1DM group (r = -0.209, p = 0.023), but no such trend was found in the control group. Analysis of data of subjects born after 1990 still showed significant delay associated with T1DM [post-T1DM group: 12.3 years (11.3-13.2), pre-T1DM group: 11.8 years (11.0-12.2), p = 0.045]. The results suggest that recent advances in insulin therapy seem to improve metabolism under T1DM but might have not enough impact on menarche in Japanese girls.