Although it is generally believed that insulin secretion is minimal or absent in juvenile-onset diabetes, we have found appreciable levels of C-peptide at the time of onset in 12 patients, 4 to 16 years old (9.3 ± 4.2). Ten of them had ketonuria but none severe ketoacidosis. All entered a remission period. Most of the patients had near normal C-peptide levels during the remission, and their beta cells had the capacity to respond to a breakfast stimulation with increased insulin secretion.
C-peptide and proinsulin were also determined in 98 juvenile diabetics with age at onset of 1 to 16 years (6.8 ± 3.9) and a duration of diabetes between two and 17 years (6.7 ± 3.4). Many were found to have persisting beta-cell function, which seems to be of importance for ensuring stability in metabolic control. Although little is known about factors that may slow or reverse the process leading to beta-cell failure, our results suggest that early detection and intensive treatment of diabetes before severe metabolic disturbances have occurred may help preserve beta-cell function.