Abstract
Seventeen insulin dependent diabetics were studied after two to four weeks of insulin treatment in a situation approximating to their normal daily life. Some endogenous insulin secretion, assessed by plasma C-peptide determinations, was present in all. Plasma C-peptide concentration was positively correlated with the blood glucose concentration and increased after breakfast, lunch and dinner (p<0.01); both peak values and relative increases were lower than those observed in normal subjects (p<0.01). The highest insulin secretory capacity was found in subjects with the least unstable blood glucose concentration (r=0.57, p <0.03), and these patients required the smallest insulin doses (r=0.54, P<0.04). These findings demonstrate the metabolic importance of a preserved B-cell function.