Cyclical disturbance of diabetic control in girls before the menarche.

Seven diabetic girls who presented with cyclical disturbance of diabetic control before the menarche are described. In six girls cyclical hyperglycaemia occurred and in one cyclical hypoglycaemia. The index case is described in detail, and is then included in a description of the main clinical features of all seven cases. Cyclical disturbance of diabetic control may present in diabetic girls from age 9 years onwards. Home blood glucose monitoring records may reveal cyclical disturbance, usually hyperglycaemia, and usually occurring at 21-34 day intervals and lasting for two to five days. Serious illnesses and hospital admission can be averted by educating parents to make appropriate changes to insulin regimen or diet. Our hypothesis is that the disturbance of diabetic control is caused by the onset of cyclical hormonal changes, a 'menstrual' cycle before menstruation. The precise mechanism for the changes in carbohydrate tolerance is unknown.