OBJECTIVE Increased levels of C-peptide, a cleavage product of proinsulin, circulate in patients with insulin resistance and early type 2 diabetes, a high-risk population for the development of a diffuse and extensive pattern of arteriosclerosis. This study tested the hypothesis that C-peptide might participate in atherogenesis in these patients. METHOD AND RESULTS We demonstrate significantl...

BACKGROUND Both C-peptide and nicotinamide are known to reduce blood glucose in type 1 diabetes. In the present study, the effects of C-peptide alone or in combination with nicotinamide on glucose and insulin levels in streptozotocin-nicotinamide-induced type 2 diabetic mice. METHODS The study used 70 adult male NMARI mice, weighing 25-35 g, divided into seven groups: control; type 1 diabetic...

OBJECTIVE We aimed to describe the natural history of residual insulin secretion in Type 1 Diabetes TrialNet participants over 4 years from diagnosis and relate this to previously reported alternative clinical measures reflecting β-cell secretory function. RESEARCH DESIGN AND METHODS Data from 407 subjects from 5 TrialNet intervention studies were analyzed. All subjects had baseline stimulate...

The in vivo hepatic metabolism of connecting peptide (C-peptide) in relation to that of insulin has not been adequately characterized. A radioimmunoassay for dog C-peptide was therefore developed and its metabolism studied in conscious mongrel dogs, with sampling catheters chronically implanted in their portal and hepatic veins and femoral artery. The hepatic extraction of endogenous C-peptide ...

It is generally recognized that the connecting peptide (C-peptide) of proinsulin fulfills an important function in the biosynthesis of insulin. It brings together the A-and B-chains such that the initial folding and interchain disulfide bonds can be formed. Evolutionary considerations suggest that a length of approximately 30 residues for the connecting segment, as is the case for human C-pepti...

C-peptide is produced, processed, and secreted with insulin, and appears to exert separate but intimately related effects. In this review, we address the existence of the C-peptide receptor, the interaction between C-peptide and insulin, and the potential physiological significance of proinsulin C-peptide.

C-peptide is a widely used measure of pancreatic beta cell function. It is produced in equimolar amounts to endogenous insulin but is excreted at a more constant rate over a longer time. Methods of estimation include urinary and unstimulated and stimulated serum sampling. Modern assays detect levels of c-peptide which can be used to guide diabetes diagnosis and management. We explore the eviden...

Of the four endogenous members of the natriuretic peptide family, only atrial natriuretic peptide has been demonstrated to have neuromodulatory effects. This study compares the neuromodulatory effects of atrial natriuretic peptide and a recently identified natriuretic peptide, C-type natriuretic peptide, in the rabbit isolated vas deferens. The ability of these peptides to alter cyclic nucleoti...

Aim To determine whether the low C-peptide levels (< 50 pmol/l) produced by the pancreas for decades after onset of Type 1 diabetes have clinical significance. Methods We evaluated fasting C-peptide levels, duration of disease and age of onset in a large cross-sectional series (n = 1272) of people with Type 1 diabetes. We then expanded the scope of the study to include the relationship between ...