ABSTRACT
Glycated haemoglobin (HbA1C) is being reported to vary in level for a given blood glucose range from individual to individual especially along racial line. This study was therefore carried out to investigate the local HbA1C normal level and determine extent of (if any) variation from the World Health Organization(WHO) recommended threshold for the onset of diabetes mellitus(DM) and pre-diabetes using blood glucose as a benchmark. And also look into the correlation between glycated hemoglobin A1c (HbA1c) and the risk of developing diabetic nephropathy among diabetic patients attending Ahmadu Bello University Teaching Hospital (ABUTH) Zaria, Nigeria and determine the level or range of glycated hemoglobin at which the risk of nephropathy becomes pronounced. One hundred and fifty two (152) volunteer subjects were used for the study comprising of 101 diabetic subjects and 51 non-diabetic control subjects. Blood sample, 5ml, was collected from each of the subjects after about 8 to 10 hours of overnight fasting. About 3ml of the sample was centrifuged and the serum analysed for fasting blood glucose (FBG) and serum creatinine (SCr). The Glomerular Filtration Rate (GFR) was then calculated from the serum creatinine values using Cockroft-Gault equation. The remaining volume of blood, about 2ml, was transferred into EDTA bottles and analysed immediately for glycated haemoglobin (HbA1C).Thirty-seven (37) of the diabetic subjects and twenty-three (23) of the non-diabetic subjects had mean HbA1C levels of 6.96% and 6.29% respectively that correspond to mean FBG levels of 91.37mg/dL and 79.16mg/dL respectively. No significant correlation was found between HbA1c and GFR but on selecting subjects with HbA1c level ≥ 9% and testing the correlation between their HbA1c and GFR, the correlation became significant and negatively (r= -0.35). The glycated haemoglobin (HbA1c) levels of diabetic patients attending Ahmadu Bello University Teaching Hospital and non-diabetic control subjects was distinctly higher for a given blood glucose range. Also, diabetic patients with HbA1c levels ≥ 9% had a significantly lower GFR.