INFLUENCE OF AGE AND GENDER ON THE LEVELS OF GLYCOSYLATED HAEMOGLOBIN AMONG NON-DIABETIC NIGERIAN SUBJECTS

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ABSTRACT

The influence of age and gender on the levels of glycosylated haemoglobin among non-diabetic Nigerians 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 really 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 mean ± standard deviation for continuous variables and statistical significance accepted at p ˂ 0.05. The results obtained showed that glycosylated haemoglobin (HbA1c) increased across the age groups (4.27 ± 0.64, 4.97 ± 0.61, 5.13 ± 0.71, and 5.26 ± 0.49 for age groups ≤ 20, 21 – 40, 41 – 60 and above 60 years respectively). These increase were found to be significant (p < 0.05) from each other. A positive correlation was also observed between age and HbA1c levels. There was no significant (p > 0.05) association between HbA1c and gender. The results did not show any correlation between HbA1c and gender. The study showed that HbA1c is positively correlated (p = 0.01) with body mass index (BMI). The mean BMI for men increased with age up to the 41 – 60 year-old age group and then declined, while the average values for women increased across the age groups. Men had the highest mean BMI in the 41 – 60 year-old age-group, while women had the highest mean BMI in the age group above 60. Generally, women had higher mean BMI than men. The mean values obtained at the different age groups were significant (p < 0.05) compared with each other within each gender except at age group 21- to 40-year old in women. Thus this study showed that age and BMI positively correlated with the levels of HbA1c in normal glucose tolerant individuals whereas gender did not. Consequently, it may be necessary that their contributions are taking into account when making diagnostic and therapeutic decisions with regard to diabetes care using HbA1c. From this study, an HbA1c range of (4.0 – 5.2) % could be considered as the normal range for individuals below sixty one years while HbA1c level of ≤ 5.27% is suggested for individuals above sixty years. However, further studies is 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 play in diabetes management and diagnosis.