Beta-cell function and metabolic control in insulin treated diabetics

Abstract

In a random one day study beta-cell function was evaluated in 210 insulin treated diabetics by the serum C-peptide concentration 6 min after iv injection of 1 mg of glucagon. Sixty-five patients (31%) had residual beta-cell function. As a group these patients were characterized by having a higher age at onset of diabetes (P < 0.01), a shorter duration of disease (P < 0.01) and by receiving a smaller dose of insulin (P < 0.01). However, their quality of metabolic control did not differ from the patients without beta-cell function. Although the concentrations of post-stimulatory C-peptide correlated inversely with both the 24-hour glycosuria (P <0.01) and the fasting blood glucose concentrations (P < 0.02), only a subgroup with C-peptide concentrations exceeding 0.30 pmol/ml showed a definitely better degree of metabolic control than those without beta-cell function. As this subgroup also received the smallest dose of insulin these observations suggest that maintenance of beta-cell function above this level facilitates good metabolic control.Evidence is presented suggesting that measurements of the 24-hour glycosuria undertaken in a diabetes clinic create a too optimistic impression of the quality of metabolic control during every day life.

Prevalence of residual B cell function and its metabolic consequences in Type 1 (insulin-dependent) diabetes

“…Conflicting results have been presented [26, 56-59, 70, 71, 81-84]. In 210 Type 1 diabetic outpatients [84], no difference was found in control between patients with and without B cell function. Patients with endogenous insulin secretion were treated with a smaller daily dose of insulin and more often with only one daily dose compared with patients without B cell function.…”

“…Only a subgroup with a post-stimulatory C-peptide level exceeding 0.30 nmol/1 (~ 25% of that found in normal subjects) had better metabolic control than patients without B cell function. In 65 patients with B cell function, there was a significant inverse correlation between C-peptide and glycosuria [84]. This may be a direct consequence of endogenous insulin secretion, but could also be explained by the relationship between glycaemic control and B cell function [30,32].…”

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

“…There were many reports which metabolic stability in NIDDM resulted from residual beta-cell function (Hendriksen et al 1977 ;Binder andl Faber 1978;Madsbad et al 1980). On the other hand, there were a few reports about correlation between residual beta-cell function and metabolic stability in IDDM (Faber and Binder 1977a ;Sjoberg et al 1987).…”

“…Many clinicians have experienced that from the point of view of metabolic consequence by insulin treatment, there were two groups, stable IDDM and unstable IDDM who did not have any residual beta-cell function when residual beta-cell function was checked by conventional method. The positive correlation between residual beta-cell function and metabolic consequence in NIDDM (Binder and Faber 1978;Madsbad et al 1980) leads us to consider that metabolic consequence in IDDM may also result from minimal reserve of beta-cell function.…”

Does C-peptide have a physiological role?

“…Some patients with IDDM maintain a level of pancreatic beta-cell activity for many years after onset of the disease [13,14]. Residual insulin secretory activity in these patients has been suggested to be associated with improved blood glucose control in cornparison with patients without such activity [15,16].…”