Brittle diabetes in the elderly.

Severely unstable, or brittle, diabetes can be disruptive to patients, carers and diabetes care teams. The peak age-group for brittle diabetes is 15-30, but there are reports of its occurrence in much older patients. To explore the characteristics and cause of brittle instability perceived by diabetologists in elderly patients we circulated a questionnaire to all UK hospital diabetic clinics for adults. 130 (56%) of 231 replied. Reports were obtained on 55 patients fulfilling our criteria for 'elderly brittle diabetes'--namely, age > or =60 years, on insulin treatment, and experiencing life-disrupting glycaemic instability of any kind associated with frequent or long admissions to hospital. Further information was obtained by a research nurse who visited the relevant clinics. The mean age of patients was 74 years (range 60-89) and 71% were female. The brittleness was classed as mixed glycaemic instability in 22 (44%), recurrent ketoacidosis in 16 (29%) and recurrent hypoglycaemia in 15 (27%). In 2 cases there was insufficient information for classification. The diabetes care team judged the brittleness to have multiple origins in two-thirds of the cases: problems with memory or behaviour were rare, and in only 4 cases was deliberate manipulation of therapy considered a possibility. 84% of the patients were living independently. In younger patients the principal manifestation of brittle diabetes is recurrent ketoacidosis. The present survey, though possibly subject to ascertainment bias, indicates that the patterns of instability and their causation may be different in elderly patients. With the growing use of insulin in the elderly, brittle diabetes is likely to be encountered increasingly often in this age-group.