The spectrum of brittle diabetes.

A group of 42 severely brittle insulin dependent diabetic patients were studied, and compared with a similar number of 'stable' diabetic patients. Brittle diabetics were predominantly female (86% v 45%, P < 0.01), were of younger age (mean +/- SD 27.9 +/- 12.8 years v 40.1 +/- 13.6 years, P < 0.001), and of shorter duration of diabetes (13.7 +/- 9.4 years v 19.6 +/- 11.2 years, P < 0.01). Control as measured by glycosylated haemoglobin (HbA1) was poorer (13.7 +/- 3.1% v 10.1 +/- 1.5%, P < 0.001), and daily insulin dose higher (98 +/- 81 u v 47 +/- 14 u, P << 0.001). There was no difference in diabetic complication rates, but psychosocial disturbances (74% v 17%) and factitious instability (40% v 2%) were highly significantly more common amongst brittle patients. Examination of patterns of admission revealed most brittle diabetics to have hyperglycaemic problems (70%), mainly due to recurrent ketoacidosis (52%). Recurrent hypoglycaemia accounted for 12% of the group, and only 5/42 patients (12%) had mixed forms of instability. Brittle diabetes is thus characterized by young age and female sex, and usually manifests itself as recurrent ketoacidosis or other forms of hyperglycaemic instability. Psychosocial problems and factitious metabolic decompensation are common.