Abstract
ObjectiveTo clarify the association between C-peptide index and pancreatic beta cell function and diabetes.Materials and methodsWe carried out a retrospective analysis of 1021 patients aged 27 to 80 without diabetes from January 2012 to January 2016. All subjects underwent a 75-g oral glucose tolerance test. Blood samples were drawn at 0, 30, 60, 120 and 180 min after the glucose load. Plasma glucose concentrations, serum insulin levels, C-peptide levels, hemoglobin A1c (HbA1c), and other biochemical indicators were determined. C-peptide index was calculated as the ratio of C-peptide to plasma glucose. Disposition index was calculated as the result of the insulin sensitivity × insulin secretion. Area under the receiver operating characteristic curve was used to compare the diagnostic ability of C-peptide index for type 2 diabetes.ResultsC-peptide index 1h was the most related one to disposition index (r = 647, p<0.001) and C-peptide release (r = 0.879, p<0.001). Both C-peptide index 1h (Exp(β) = 0.28, p<0.001) and 2h (Exp(β) = 0.42, p<0.001) were independently associated with disposition index, but the OR of C-peptide index 1h for diabetes was much lower. Area under the receiver operating characteristic curve of both C-peptide index 1h and 2h were all above 0.9, but the area of C-peptide index 1h was the highest one (0.937 vs 0.917). C-peptide index 1h has the highest diagnostic value (sensitivity = 90%, specificy = 85.2% vs sensitivity = 83.5%, specificy = 87.9%).ConclusionC-peptide index after oral glucose ingestion may reflect the maximal β-cell function and is more related to diabetes. C-peptide index 1h is the most relevant one.
Highlights
Progressive pancreatic β-cell function failure and insulin resistance are the key characteristics of type 2 diabetes mellitus (T2DM)
In ROC curve analysis, we found that C-peptide index (CPI) 1h has the highest diagnostic value to predict diabetes mellitus (AROC = 0.937, sensitivity = 90%, specificy = 85.2%)
Glucose itself is a major stimulus of β-cells, insulin secretion is incremented by hyperglycemia seen in patients with diabetes
Summary
Progressive pancreatic β-cell function failure and insulin resistance are the key characteristics of type 2 diabetes mellitus (T2DM). Once the excessive secretion of insulin can no longer compensate for the degree of insulin resistance, clinically significant hyperglycemia will happen. Insulin secreted from pancreatic β-cells will be partially cleared in the liver before entering the peripheral circulation [1, 2]. The concentration of insulin calculated in peripheral blood can’t represent the total amount of insulin secreted by the pancreas. C-peptide secreted with insulin in equimolar amounts is not cleared in the liver. The peripheral plasma C-peptide concentrations reflect endogenous insulin secretion more accurately than serum insulin [3]. C-peptide is capable of assessing beta cell function even in patients under insulin therapy [4]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have