Background: Endocrine action is integrative and an endocrine dysfunction of one gland is known to affect other endocrine glands. Parathyroid glands are associated with the beta cell function. Thus, insulin resistance observed in type 2 diabetes mellitus (T2DM) may be associated with alterations of parathyroid hormones and their metabolic pathways. These have been reported to have a genetic root, postulated to be aberrant haemoglobin gene resulting in haemoglobin variants. This has not been fully explored in sub-Saharan Africa, which has significant population of haemoglobin variants. Aim: The aim of this study was to evaluate the status of parathyroid dysfunction and its association with haemoglobinopathies among Sub-Saharan Africans with type 2 diabetes mellitus. Method: A total of 204 individuals aged 25 – 80 years which comprised 100 T2DM and 104 Controls without T2DM were enrolled from a tertiary hospital, in Ibadan, Nigeria and environs.10mL intravenous blood was obtained from each participant. Parathyroid Hormone (PTH) was measured using enzyme linked immunosorbent assay (ELISA). Calcium, Phosphate, Albumin and Fasting Plasma Glucose (FPG) were analysed spectrophotometrically. Haemoglobin A2 (HbA2), Haemoglobin A (HbA), Haemoglobin C (HbC) and Haemoglobin S (HbS) and Glycated haemoglobin (HbA1c) were determined by High Performance Liquid Chromatography (HPLC) method using Variant Haemoglobin Testing System (Bio-Rad Variant II). Data analysed using appropriate statistical analysis were significant at p<0.05. Results: Normal parathyroid function, hyperparathyroidism and hypoparathyroidism were present in 93% vs 96%, 3% vs 0.96% and 4% vs 6.73% in T2DM and controls respectively. T2DM and controls with AA and Non AA had 62% vs 31% normoparathyroidism, 3% vs 0% hyperparathyroidism and 2% vs 2% hypoparathyroidism respectively. The association between parathyroid gland disorder in T2DM and controls with the various haemoglobin variants was not significant (p>0.05) but the difference between parathyroid function in the control group with and without Beta Thalassaemia Trait was significant (p<0.05). Conclusion: Hypoparathyroidism and hyperparathyroidism were revealed in Type 2 Diabetes Mellitus and control individuals with haemoglobin genotype AA (HbAA). Hypoparathyroidism was also found among controls with Beta Thalassaemia Trait. Timely identification of these disorders may be helpful in appropriate therapeutic regimen to facilitate bone growth, prevent fractures and complications of parathyroid gland in these individuals. KEYWORDS: Haemoglobin Variants, Parathyroid Dysfunction, Type 2 Diabetes Mellitus (T2DM).

Background: Beta thalassaemia trait (BTT), a beta globin gene disorder share insulin resistance with Type 2 Diabetes Mellitus (T2DM). BTT may therefore be a risk factor for T2DM. We hypothesise that undiagnosed BTT could be a risk factor for T2DM. Methods: BTT was compared between 99 individuals with T2DM and 105 apparently healthy individuals in an unmatched case-control study. Red cell indices and haemoglobin fractions were analysed using an electronic cell counter and HPLC respectively. Findings: T2DM individuals were a decade older than controls, 59.6 years vs. 46 years (p=0.001), more likely to be women. T2DM had a lower mean haematocrit, 37.3% vs. 40.6% (p=0.001). Though the mean HbA2 was higher in T2DM (2.6% vs. 2.4% (p=0.03)) the prevalence of BTT was twice as high in the control 8% vs. 4%. More T2DM had the Sickle Cell Trait (SCT) 27.3% (27/99) vs. 15.2% (16/105); p=0.035. The mean HbA2 for individuals with SCT was higher than for individuals without the trait (3.1% vs. 2.4%; p=0.001). All T2DM with BTT had the SCT while six of the eight controls with BTT had SCT. T2DM with BTT were older, more likely to be women and had a lower haematocrit, red cell indices than controls with BTT but both had similar RDW and HbA2. Conclusion: The higher HbA2 in SCT, T2DM and a higher prevalence of SCT in T2DM may be linked to the presence of BTT. Apparent protection of T2DM by BTT may be because of early deaths of T2DM with BTT. T2DM may therefore differ between those with BTT and those without.