Correlation of Plasma HbA1c with Serum Nitric Oxide Levels in Type 2 Diabetics

Abstract

Background: Type 2 diabetes mellitus (T2DM) is associated with chronic hyperglycaemia, endothelial dysfunction, and progressive microvascular complications. Microalbuminuria is an early marker of diabetic nephropathy, while glycated hemoglobin (HbA1c) reflects long-term glycaemic control. Alterations in nitric oxide (NO) metabolism have been implicated in endothelial dysfunction; however, the relationship between serum NO, HbA1c, and microalbuminuria across different age groups remains incompletely understood. This study evaluated serum NO and HbA1c levels in T2DM patients with and without microalbuminuria and examined their association.

Methods: A hospital-based cross-sectional study was conducted among 200 patients with T2DM aged ≥30 years attending a tertiary teaching hospital. Participants were categorized into Group I (normoalbuminuria; n=123) and Group II (microalbuminuria; n=77). Serum nitric oxide was estimated using the Griess reagent assay, HbA1c was measured by standard laboratory methods, and 24-hour urinary albumin was quantified. Data were analyzed using SPSS version 17.0. Continuous variables were expressed as median (interquartile range), group comparisons were performed using the Mann–Whitney U test, and Spearman's rank correlation was used to assess the association between HbA1c and serum NO.

Results: Patients with microalbuminuria demonstrated significantly higher serum NO and HbA1c levels than normoalbuminuric subjects, particularly in the 30–45 and 45–55-year age groups (P-value<0.001). A significant positive correlation was observed between serum NO and HbA1c levels (Spearman's ρ=0.34, P-value<0.001), indicating that worsening glycaemic control was associated with increased circulating nitric oxide metabolites. The findings suggest that elevated serum NO may represent a compensatory response to oxidative stress and endothelial dysfunction during the early stages of diabetic nephropathy.

Conclusion: Patients with T2DM and microalbuminuria exhibit significantly higher serum nitric oxide and HbA1c levels than those without microalbuminuria. The positive association between HbA1c and serum NO suggests that poor glycaemic control is accompanied by altered nitric oxide metabolism, reflecting early endothelial dysfunction. Simultaneous assessment of HbA1c, serum NO, and microalbuminuria may provide valuable biochemical insight into the early detection and risk stratification of diabetic nephropathy, particularly among younger patients.