Lesson of the Week: Insulin dependent diabetes in nonagenarians

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Abstract
The National Diabetes Data Group's definition of insulin dependent diabetes misleadingly talks of “predominant onset in youth.”1 Over 40 years ago Lawrence wrote that many diabetic patients aged over 70 were insulin deficient.2 It has recently been shown in Denmark that the annual incidence of insulin dependent diabetes after the age of 30 is 8.2 per 100 000 and is remarkably constant from the fourth to the ninth decade; thus at least 44% of all cases are diagnosed after the age of 30.3 We report on two patients who developed insulin dependent diabetes at the ages of 88 and 93. ### CASE 1 An 88 year old woman presented with a five month history of lethargy, weight loss, and nocturia. She was found to be hypothyroid, with a high titre of thyroid autoantibodies. One of her seven siblings had developed diabetes of uncertain type at the age of 75 and a granddaughter had Graves' disease. A month later she became thirsty, was found to have diabetes, and was treated with glibenclamide 5 mg twice daily by her general practitioner. She was referred to us three months later with a random blood glucose concentration of 15.1 mmol/l and a haemoglobin A1 concentration of 11.6% (normal range 5.0%-7.5%). Apart from bilateral cataracts there were no diabetic complications, but she had a body mass index of 23 kg/m2 and was …