The Effect of Age, Gender and Haemoglobin Variants on Glycated Haemoglobin

Abstract

Aim: Glycated haemoglobin (HbA1c) is a useful screening, diagnostic and monitoring tool for diabetes. We present the effect of age, gender and haemoglobin variants on HbA1c in an African population with a high prevalence of sickle cell trait (SCT). Study Design: An unmatched case-control study. Place and Duration of Study: This was carried out in the out-patient clinic of a tertiary hospital over a one-year period. Methods: After an overnight fast, blood samples for haemoglobin fractions and HbA1c were measured in 99 individuals with T2DM and 105 apparently healthy controls using HPLC (BioRad, variant II). Results: The age for cases and controls were 25-80yrs and 30-80yrs respectively, male:female ratio were 1:3 and 1:1.4 respectively. Women were seven times more likely to have diabetes in the sixth decade than men. SCT was found in 31% of T2DM women but only in 20% of men (P=.33). T2DM women had a higher HbA1c (58mmol/mol (7.5%) vs 48mmol/mol (6.5%) (P=0.1)). Healthy women also had a significantly higher HbA1c than men, 38 mmol/mol (5.6%) vs 32 mmol/mol (5.1%) (P=.007). HbA1c was consistently higher in individuals with sickle cell trait (HbAS) than those without the trait in both groups. HbA1c did not differ between age groups in T2DM F (4, 92) =2.62, P= .81 nor in controls F (4, 96) =2.06, P=.09. There appears to be a complex interaction between gender and age groups on HbA1c in both T2DM and healthy controls, but the interaction was more pronounced in the T2DM group. There was a stronger correlation between fasting plasma glucose and HbA1C which was stronger controls than the T2DM group ((r= 0.23, P=.02) vs (r=0.12, P=.25)). Conclusion: The association between age, gender and SCT on HbA1c was more pronounced in women, this may be an interplay between socioeconomic, hormonal and genetic factors.