Warning symptoms of hypoglycaemia during treatment with human and porcine insulin in diabetes mellitus

32 subjects with long-term insulin-dependent diabetes mellitus (IDDM) were entered into a double-blind, randomised crossover trial with human and porcine insulin. They were treated during both periods with regular insulin and with protamine (NPH) insulin. 18 subjects started with human and 14 with porcine insulin; the two insulin periods each lasted twelve weeks; the insulin doses were much the same in the two periods (mean 23 [SD 9] U daily NPH; 14 [7] U daily regular insulin), as were blood glucose profiles and HbA1c values. There were 171 episodes of hypoglycaemia during human and 150 episodes during porcine insulin. Patients completed questionnaires after each hypoglycaemic episodes and at the end of the trial. Hunger and sweating without concomitant neuroglycopenic symptoms were significantly more frequent as initial warning symptoms during porcine than during human insulin (41% vs 20%), whereas neuroglycopenic symptoms were more frequent during human insulin. At the end of the trial 18 of 32 subjects reported diminished awareness of hypoglycaemia during human insulin compared with 6 of 32 during porcine insulin. Hypoglycaemia developed faster during human than during porcine insulin administration. The transfer of IDDM subjects from porcine to human insulin seems to alter warning symptoms of low blood glucose concentration, with consequent impairment of its early recognition.