IMPROVED METABOLIC CONTROL PRESERVED BETA-CELL FUNCTION 2 YEARS AFTERDIAGNOSIS OF INSULIN-DEPENDENT DIABETES-MELLITUS

To determine whether improved metabolic control during the first two y ears of insulin-dependent diabetes (IDDM) modified beta cell function, we studied 108 subjects with recent-onset IDDM diagnosed between Marc h 1986 and April 1992 and followed up prospectively for 2 years. Two i nsulin regimens were used : I) conventional insulin treatment (CIT) (1 986-90, n = 67) involving a mixture of regular and intermediate insuli n before breakfast and dinner; and 21 intensive insulin treatment (IIT ) (1990-92, n = 41) providing regular insulin before breakfast and lun ch, and a mixture of regular and long-acting insulin before dinner. Gl ucagon-stimulated C-peptide was determined at diagnosis and at 3, 6, 1 2 and 24 months. Both groups had similar clinical, metabolic and immun olnological characteristics at diagnosis. The IIT group had better met abolic control at. any given time-point after diagnosis (mean HbA1 dur ing follow-up in CIT: 9.86+/-0.28%; IIT: 8.18+/-0.04%; p<0.001) (norma l <9.0 %). C-peptide was increased in the IIT group 3 and 6 months aft er diagnosis (month 0: 0.36 +/- 0.05 nmol/l; month 6: 0.55 +/- 0.06 nm ol/l; p < 0.006), but not in the CIT group (month 0 : 0.39 +/- 0.04 nm ol/l; month 6 : 0.45 +/- 0.04 nmolil; p = NS). Two years after diagnos is, the IIT group maintained initial C-peptide secretion (2 years: 0.3 7 +/- 0.04 nmol/l, whereas C-peptide was reduced in the CIT group (2 y ears :0.23 +/- 0.06 nmol/l) compared to the initial value (p < 0.001) or to that of the IIT group (p = 0.017). Thus, sustained improvement i n metabolic control with IIT resulted in better beta-cell function dur ing the first two years after IDDM diagnosis.