Insulin‐dependent diabetes of over 50 years' duration — clinical and biochemical features

We have investigated the clinical and biochemical features (including C‐peptide responsiveness) in 10 patients with insulin‐dependent diabetes (IDDM) of over 50 years' duration (Nabarro Medal Winners). Age (mean ± SD) was 67 ± 7 years and diabetes duration 54 ± 2 years. Serum C‐peptide was undetectable both fasting and 2 hours after 1 mg intramuscular (I/M) glucagon. Glycosylated haemoglobin (HbA₁) was 10.0 ± 1.5% and cholesterol 6.2 ± 0.7 mmol/1. Only one had hypertension and only one was obese (BMI > 30.0). Four (40%) had microvascular complications (4 retinopathy, 1 nephropathy and 1 neuropathy). None were blind, had amputations, or required renal support therapy. Large vessel disease was present in only 1 (mild, stable angina). This group thus represented patients with “true” IDDM, who for their long diabetes duration were remarkably fit and relatively free of complications (particularly macrovascular). Further detailed investigation of larger numbers of Nabarro Medal Winners may provide valuable clues as to “protective” factors operating in the evolution of complications in IDDM.