It seems rational to consider that residual insulin secretion is one of the factors which determine the short-term course of inaugural type I diabetes. But what about the mid-term course? We evaluated prospectively the insulin reserve (fasting and post-prandial C peptide) in 52 patients throughout the subsequent development of the disease. The patients (36 men, 16 women, mean age 35 years), who presented with ketonuria and weight loss, received a 10-day course of intensive insulin therapy, after which a remission of insulin dependence was observed in 40 of them (77 per cent). These 40 patients differed from those who had no such remission in that they were heavier and had a better initial insulin secretion. There was no significant difference between the two groups with regards to immunogenetic markers (presence of anti-islet antibodies 28/35 vs 8/12, DR3 and/or DR4 tissue group 27/37 vs 8/10). Following intensive insulin therapy, the C peptide value was consistently increased. At 6, 12 and 18 months the insulin secretion in patients of the remission group remained stable and always higher than that of patients who did not have a remission and whose insulin secretion collapsed at 18 months. Another characteristic of the remission group was that C peptide secretion could be stimulated by meals throughout the follow-up period (post-prandial C peptide at 18 months: 0.63 nmol/l). It is concluded that residual insulin secretion is one of the most effective predictive factors of remission when type I diabetes is first diagnosed and remains stable for the first 18 months of the disease in patients who show a remission.
