Evaluation of thyroid function in diabetes mellitus in Calabar, Nigeria

The prevalence of abnormal thyroid hormone levels in diabetes mellitus in Nigeria is not well described. To determine the incidence of abnormal thyroid hormone levels in diabetics in Calabar, Nigeria, fasting blood samples from 161 diabetic subjects and 105 non-diabetic controls were analysed. Free thyroxine (FT), thyroid stimulating hormone (TSH), total triiodothyronine (T(3)) and total thyroxine (T(4)) kits obtained from Biomerica Inc. of USA were used for the analysis. TSH levels (1.80±1.62) in diabetics were significantly lower (p=0.016) than the level in non-diabetic controls (2.34±1.24). Male diabetics had lower (p<0.05) levels of TSH (1.192±0.68 miu/ml) than diabetic females (1.90±1.70 mlu/mt). The level of T(3) in diabetic males (125±97ng/ml) was higher than the level in females (98±75ng/dl). TSH (F=2.74, p=0.049), T(4)(F=56.87, p=0.001), T(3)(F=56.44, P=0.001) in diabetics and FT(4) (F=5.74, p=0.002) in controls showed significant variation with the ages of the subjects. Out of 161 diabetics subjects studies 26.6% had low plasma thyroid hormone levels (FT(4)>2.01 ng/dl). This study has shown a high incidence (46.5%) of abnormal thyroid hormone levels among the diabetics in Nigeria (hypothyroidism 26.6%, hyperthyroidism, 19.9%). The prevalence of hypothyroidism was higher in women (16.8%) than in men (9.9%), while hyperthyroidism was higher in males (11%) than in females (8%). This study has defined thyroid function status of diabetics in Calabar, Nigeria probably the first of such work in Africa.