J Korean Diabetes Assoc.  1999 Apr;23(2):147-154.

Plasma Proinsulin Levels among the Control, Impaired Glucose Tolerance and Type 2 Diabetes Mellitus during Oral Glucose Tolerance Test

• Lee MD
• Kim YU
• Kim HS
• Shin YG
• Chung CH

Abstract

BACKGROUND: Increased secretion of proinsulin has been associated with beta-cell dysfunction. Hyper-proinsulinemia is suggested to be a predictor for the progression of IGT to type 2 DM. In this study, we compared the concentration of insulin, C-peptide and proinsulin levels among the control group, IGT and type 2 DM group during the oral glucose tolerance test. We investigated whether hyperproinsulinemia was an effective predictor of beta-cell impairment befre the clinical onset of type 2 diabetic subjects.
METHODS
We studied proinsulin, insulin(using an assay that display appreciable cross-reactivity with proinsulin) and proinsulin:insulin ratio during the oral glucose tolerance test in 14 controls, 20 IGT and 20 type 2 DM. We also compared proinsulin, proinsulin response areas and proinsulin:insulin ratio among the three groups.
RESULTS
There were no significant differences in the baseline and 30min proinsulin levels among three groups. However, proinsulin response areas in IGT were higher than those in other groups. Baseline proinsulin/insulin ratio and post-load proinsulin/ insulin ratio were not significantly different among the three groups. In IGT group, the proinsulin response after glucose loading was rapidly increased, but was blunted in diabetic patients.
CONCLUSION
We suggest that pancreatic beta cell dysfunction was ongoing before the clinical onset of DM and hyperproinsulinemia, especially the proinsulin response areas during oral GTT may be a predictor for the development of type 2 DM.

Keyword

Proinsulin; Impaired glucose tolerance; Type 2 diabetes mellitus

MeSH Terms

C-Peptide
Diabetes Mellitus, Type 2*
Glucose Tolerance Test*
Glucose*
Humans
Insulin
Insulin-Secreting Cells
Plasma*
Proinsulin*
C-Peptide
Glucose
Insulin
Proinsulin