Residual β-Cell Function in Children With IDDM: Reproducibility of Testing and Factors Influencing Insulin Secretory Reserve

Abstract

Reproducibility of C-peptide secretion was assessed in 20 children (group 1) by their responses to two Sustacal- (a mixed liquid meal) stimulation tests performed 7-14 days apart. For the 12 C-peptide-positive children (basal C-peptide greater than or equal to 0.03 pmol/ml) there were no differences in the basal or stimulated values between tests 1 and 2. The effect of exogenous insulin on C-peptide secretion was assessed in 20 other children (group 2) by their responses to two Sustacal tests, one test without and one with soluble insulin (0.25 U/kg) injected subcutaneously before testing. Eleven children were C-peptide positive and had no differences in C-peptide response between tests 1 and 2. The results from test 1 in groups 1 and 2 were combined with those from 44 others undergoing a single Sustacal test (group 3, N = 84). There was a close correlation between basal and peak C-peptide concentrations in the 44 C-peptide-positive children (r = .88, P less than .001). Peak C-peptide concentrations correlated inversely with HbA1 (r = -.29, P less than .01), insulin dose in units per kilogram (r = -.40, P less than .001), and duration of diabetes (r = .33, P less than .001) and positively with age at onset of diabetes (r = .34, P less than .001). The C-peptide-positive children had reduced glucose response to Sustacal, lower HbA1 concentration, lower insulin requirement, later age of onset, and shorter duration of diabetes than children who were C-peptide negative.

Residual B Cell Function in Patients with Long-Standing NIDDM and its Relation to Metabolic Control and Diabetic Complications.

“…Serum C-peptide response to glucagon in patients treated with sulfonylurea or insulin in the present study was substantially the same as the reported values (Matsuda et al, 1985) and it was suggested that the residual B cell function was not lowered in long-standing NIDDM, being consistent with previous studies (Lev-Ran et al, 1986;Snehalatha et al, 1986). Some reports on IDDM indicated that the more active the residual B cell function, the better the metabolic control (Gonen et al, 1979;Clarson et al, 1987;Sjoberg et al, 1987). The present study on NIDDM, however, differed from them in that the residual B cell function did not significantly correlate with the glycemic levels at the first visit, through the observation period and at present.…”

Honey and Type 1 Diabetes Mellitus

“…However, they reported different basal values which can respond to stimulation. Such values were 0.09 (Clarson et al, 1987), 0.18 (Eff et al, 1989 and 0.39 ng/ml (Faber & Binder, 1977). The variation in these levels was probably due to the different ages and different diabetes duration of the studied populations (Pozzan et al, 1997).…”

The C-peptide response to a standard mixed meal in a group of Brazilian type 1 diabetic patients

“…To reproduce as much as possible the usual condition of the patients, we decided to maintain their usual insulin dose before the test meal. One study (2) reported no difference in C-peptide response to Sustacal ® , with and without the use of exogenous insulin. In that study, as in the present report, no patient developed hypoglycemia during the test.…”

“…The determination of C-peptide is a widely used method to evaluate residual insulin secretion in type 1 diabetic patients using exogenous insulin (1)(2)(3)(4)(5). However, comparison between the studies is impaired by the variety of methods of stimulation used and time of sampling.…”