Thyroid dysfunction among patients with type 2 diabetes mellitus at Moi Teaching and Referral Hospital, Eldoret, Kenya

Abstract

Background: Thyroid dysfunction is more prevalent among patients with diabetes (10- 24%) compared to the general population (2-7%). Coexistence of thyroid disorders among patients with diabetes results in impaired lipid metabolism, endothelial dysfunction and impaired glycemic control. These risk factors have been implicated in worsening of cardiovascular disease which is the leading cause of death in diabetes. Early recognition and treatment of thyroid dysfunction in diabetes is important for mitigation of associated cardiac complications. Whereas diabetes is common in our region, little is known about the prevalence of thyroid dysfunction among patients with diabetes. Objectives: To determine the prevalence and clinical correlates for thyroid dysfunction among patients with Type 2 Diabetes Mellitus (DM) in Moi Teaching & Referral Hospital (MTRH). Methods: This was a cross-sectional study conducted at the diabetes outpatient clinic in MTRH between February and April 2018. The study population included 2500 ambulatory patients with Type 2 DM, aged 35 years and above at the time of diagnosis, out of which 368 participants were enrolled by systematic random sampling. Structured interviewer administered questionnaires were utilized to collect socio-demographic, clinical and laboratory data. Third generation immunoassays were used for measurement of Thyroid Stimulating Hormone (TSH), glycated hemoglobin (HbA1c) and low-density lipoprotein-cholesterol (LDL-C). Descriptive statistics such as the median and interquartile ranges were used to summarize continuous variables. Frequencies and percentages were used to summarize categorical variables. Association between thyroid dysfunction and categorical independent variables was assessed using Pearson’s Chi Square test. Fisher’s exact test was reported whenever the Chi Square assumptions were violated. Multiple logistic regression was used to determine the effect of independent variables on thyroid function. Results: The median age of the participants was 59.2years, with 230(62.5%) of these being females. Prevalence of thyroid dysfunction among patients with Type 2 DM was 9.2% (95%CI: 6.4, 12.7) representing 34 participants. Subclinical hypothyroidism was the most frequent dysfunction at 7% (22). Sociodemographic (age, gender) and clinical characteristics (duration of Type 2 DM, insulin use, hypertension, body mass index and LDL-C) studied indicated no association with thyroid dysfunction. There was no significant correlation between thyroid dysfunction (TSH, freeT4) and glycemic control (HbA1c). Conclusion: The prevalence of thyroid dysfunction among patients with Type 2 DM is high compared to what has been reported in the general population. There was no significant correlation found between thyroid dysfunction and the studied clinical correlates. Recommendations: Routine assessment of thyroid hormone levels should be part of evaluation for patients with Type 2 DM. A prospective study should be considered to further evaluate other clinical correlates that may be associated with thyroid dysfunction.