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The influence of age and sex on the levels of glycosylated haemoglobin among non-diabetic Nigerian population were investigated in this study. Seventy-nine non-diabetic individuals volunteered for the study and were grouped into male and female and then into four groups according to age: ≤ 20 years, 21 - 40 years, 41 - 60 years and ≥ 61 years. Fasting blood glucose, 2-hour post-load glucose, packed cell volume and genotype analyses of subjects were initially determined to ensure that subjects were non-diabetic and had no glucose metabolic impairment. Subsequently, glycosylated haemoglobin and body mass index were measured. Student’s t-test, Pearson correlation and one-way analysis of variance were used to compare the data which were presented as a mean ± standard deviation. Statistical significance was accepted at p ˂ 0.05. The results obtained showed that: (1) glycosylated haemoglobin (HbA1c) significantly increased with age, (2) there is no correlation between HbA1c with sex and (3) there was a positive association between Hba1c and body mass index in normal glucose tolerant subjects. Based on the result of this study, the contributions of age and BMI to HbA1c levels should be taking into account when making diagnostic and therapeutic decisions with regard to diabetes care using HbA1c. The hba1c range of (4.0 - 5.2) % could be considered as the normal range for individuals below sixty-one years while the HbA1c level of ≤ 5.27% is suggested for individuals above sixty years. However, further studies are required especially to investigate the non-glycaemic factors affecting HbA1c levels in normal glucose tolerant populations so as to really understand the actual role glycosylated haemoglobin values play in diabetes management and diagnosis.