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.