A Pair of Identical Twins in whom the Co-twin Displayed More Rapid Insufficiency of Endogenous Insulin Secretion than the Index Twin

Abstract

We encountered a pair of identical twins with diabetes. At 29 years of age, the index twin developed diabetes with ketosis. At 31, 2 years after the onset of diabetes in the index twin, the co-twin developed diabetes with ketosis. Insulin therapy enabled a near-nomal state of metabolic control in both twins. The glucose infusion rate (GIR) showed a tendency toward insulin resistance (4.89 mg/kg/min) in the index twin, but not in the co-twin 6.17 mg/kg/min. Urinary C-peptide in the index twin was 78.8μg/day 2 years after onset, but the urinary C-peptide level in the co-twin was low (20.0μg/day). Considering all of the evidence together, the index twin may have non-insulin-dependent diabetes (NIDDM) and the co-twin insulin-dependent diabetes (IDDM). These cases provide a clue to the common pathogenesis of IDDM and NIDDM.