The Study of Comparison between Hba1c and GA%/HbA1c % Ratio as a Prognostic Indicator in Diabetic CKD Patients on MHD

Abstract

Background: Glycated haemoglobin (HbA1c) is widely used to assess long-term glycaemic control in diabetes mellitus. However, in patients with Chronic Kidney Disease (CKD), particularly those with end-stage renal disease (ESRD) on haemodialysis, factors such as renal anaemia, altered red blood cell survival and uraemia may lead to falsely low HbA1c values. Glycated albumin (GA), which is independent of red blood cell lifespan, may therefore provide a more reliable assessment of glycaemic control in this population. The present study compared HbA1c and glycated albumin and evaluated the clinical significance of the GA/HbA1c ratio in diabetic patients with ESRD on maintenance haemodialysis (MHD).

Methods: This prospective, comparative, observational study was conducted in the Department of Internal Medicine, Karnataka Institute of Medical Sciences, Hubballi, from November 2016 to July 2018. A total of 88 patients were included, comprising 44 diabetic ESRD patients on haemodialysis (cases) and 44 diabetic patients without nephropathy and not on haemodialysis (controls). HbA1c, glycated albumin, fasting blood sugar, postprandial blood sugar and other biochemical parameters were assessed. Correlations between glycaemic parameters were evaluated using Pearson’s correlation coefficient, and multivariate linear regression was performed to identify predictors of average blood glucose.

Results: The mean age was 52.7 ± 11.95 years in cases and 56.52 ± 12.38 years in controls. Mean haemoglobin was significantly lower in cases than controls (8.6 ± 1.76 vs 12.45 ± 1.49 g/dL; p<0.001), while serum creatinine was significantly higher (8.42 ± 2.94 vs 0.777 ± 0.138 mg/dL; p<0.001). Mean estimated GFR was 10.87 ± 3.47 mL/min/1.73 m² in cases compared with 98.01 ± 10.25 mL/min/1.73 m² in controls. Despite comparable fasting, postprandial and average blood glucose levels, HbA1c was significantly lower in haemodialysis patients (6.77 ± 0.95% vs 7.60 ± 1.53%; p=0.002). Glycated albumin concentration was also significantly different between groups (326.35 ± 43.3 vs 352.12 ± 39.84 ng/mL; p=0.0017), while GA% was 25.6 ± 4.32% in cases and 26.58 ± 4.96% in controls (p=0.30). The GA/HbA1c ratio was significantly higher among haemodialysis patients (3.80 ± 0.57 vs 3.51 ± 0.60; p=0.04). GA% showed a stronger correlation with average blood glucose than HbA1c in controls (r=0.652 vs 0.401) and remained significantly associated with blood glucose on multivariate analysis.

Conclusion: HbA1c may underestimate glycaemic control in diabetic ESRD patients receiving haemodialysis, particularly in the presence of renal anaemia and altered red blood cell survival. Glycated albumin demonstrated a stronger association with average blood glucose and may therefore be a useful alternative marker of glycaemic control in this population. The higher GA/HbA1c ratio observed in haemodialysis patients further supports the presence of falsely low HbA1c values in ESRD. The GA/HbA1c ratio may also have potential clinical utility as an indicator of glycaemic excursions and vascular risk.