Year : 2026

Volume : Volume 17

Issue : Issue 1

Address for correspondence :
Dr Rahul Goyal
prahulbiochemistry@gmail.com

Abstract

Background: Type 2 Diabetes Mellitus (T2DM) is characterized by insulin resistance and a progressive decline in β-cell function. C-peptide, a direct marker of endogenous insulin secretion, provides a reliable assessment of β-cell function. Glycated hemoglobin (HbA1c) reflects the average blood glucose control over the preceding 2-3 months. The relationship between dynamic β-cell function (as measured by fasting and postprandial C-peptide) and chronic glycemic control (HbA1c) in T2DM is crucial for understanding disease progression and tailoring therapy. Materials and Methods: This cross-sectional study included 110 diagnosed T2DM patients. Fasting blood samples were collected for plasma glucose, C-peptide, and HbA1c. Postprandial blood samples for glucose and Cpeptide were taken 2 hours after a standardized mixed meal. Patients were categorized into three groups based on HbA1c: Good control (HbA1c <7%, n=30), Fair control (HbA1c 7-8.5%, n=42), and Poor control (HbA1c >8.5%, n=38). Statistical analysis was performed using SPSS version 25.0. Results: The mean age of participants was 52.4 ± 8.7 years. A significant negative correlation was observed between HbA1c and both fasting C-peptide (r = -0.48, p < 0.001) and postprandial C-peptide (r = -0.62, p < 0.001). The Poor control group (HbA1c >8.5%) had significantly lower mean fasting and postprandial C-peptide levels (1.21 ± 0.45 ng/mL and 2.89 ± 0.91 ng/mL, respectively) compared to the Good control group (2.15 ± 0.61 ng/mL and 4.95 ± 1.12 ng/mL, p < 0.001). The postprandial C-peptide response (ΔC-peptide) was also markedly blunted in the poor control group. Conclusion: There is a strong inverse correlation between C-peptide levels (both fasting and postprandial) and HbA1c in T2DM patients. Patients with poorer long-term glycemic control exhibit significantly lower endogenous insulin secretion, indicating a more advanced stage of β-cell dysfunction. Regular assessment of C-peptide, especially postprandial, can be a valuable tool in clinical practice to monitor β-cell reserve and guide management strategies in T2DM