Background: Studies from different parts of the world on thyroid dysfunction have shown it to be widespread in patients with type 2 diabetes mellitus (T2DM); however, there is insufficient local data to support this observation.
Aim: To determine the burden of thyroid dysfunction among patients with T2DM at a Tertiary Hospital in South east Nigeria with emphasis on its prevalence and pattern of presentation.
Methods: Four hundred and seventy two subjects were recruited for the study. All the subjects (100%) were of African descent. Three hundred and fifty-four (354) of them were patients with T2DM, while 118 subjects who did not have T2DM served as the controls. This study is a descriptive cross-sectional study involving patients with type 2 diabetes mellitus attending the Diabetes Clinic, or receiving treatment in the Medical Wards. Subjects were recruited using systematic sampling. The first patient was selected by simple random sampling, and subsequently, every consecutive subject was selected. Blood samples were tested for HbA1c, fT3, fT4 and thyrotropin, thyroid stimulating hormone. Socio-demographic information was retrieved from patient medical records. We used the student t-test for statistical comparison of quantitative variables such as weight, height, blood pressure, serum TSH, serum T3; while for comparison of proportions, we used the chi squared test. We set a p-value of less than 0.05 to be statistically significant.
Results: Females formed the majority of the study population accounting for 56.5% of the type 2 DM patients and 62.7% of the controls. We observed that the mean age of the type 2 DM patients was 57.5 (±9.3) years, which was similar to the mean age of controls: 57.7±8.9 (p=0.17). We also observed that the mean age at diagnosis of DM was 54±7.6 years, while the mean duration of DM for all the type 2 DM patients was 6.5±2.8 years. We observed that in patients with T2DM, the prevalence of thyroid dysfunction was 12.4%, and among the controls a prevalence of 1.7% was observed (P <0.05). Females formed the majority (75%) of T2DM patients with thyroid dysfunction and hypothyroidism was the most common type of thyroid dysfunction (93.2%) observed in this study.
Conclusion: Prevalence of thyroid dysfunction in T2DM patients in this study was 12.4% which was high compared to 1.7% observed in the controls (P = 0.001). Majority of those who had thyroid dysfunction were females. About 9 in 10 of all subjects with thyroid dysfunction had hypothyroidism.