Residual beta-cell function and metabolic stability in insulin-dependent diabetes mellitus

Using the modified sensitive method of measurement of urinary C-peptide immunoreactivity (CPR) excretion, we studied whether positive correlation between residual beta-cell function and metabolic consequence is present in insulin-dependent diabetes mellitus (IDDM) or not. After urinary CPR excretions were measured for 3 days in 40 IDDM, they were divided to three groups: group A, urinary CPR excretion less than 1 microgram/day (n = 16); group B, 1-4 micrograms/day (n = 15); group C, greater than or equal to 4 micrograms/day (n = 9). All subjects were treated with intensive insulin therapy for 1-2 months, and 1) fasting blood glucose (FBS) for one week, 2) 24-hr urinary sugar excretion (US) for one week, 3) M-value for daily variation of blood glucose, and 4) hemoglobin A1 (HbA1) were measured before and after intensive insulin treatment. And, we calculated mean and standard deviation (S.D.) of FBS and US. After intensive insulin therapy, a significant difference of the S.D. of FBS was seen between group A and group B (p less than 0.01). And, a significant difference of M-value was found between group A and group B (p less than 0.05). As significant differences were observed between group A and group B, which could not be divided into two groups by conventional CPR measurement, it seems likely that metabolic stability in IDDM mainly result from minimal remaining residual beta-cell function.