ASSOCIATION BETWEEN GLYCATED HEMOGLOBIN AND ELEVATED THYROID HORMONES LEVELS IN PATIENTS WITH TYPE 2 DIABETES MELLITUS.

Abstract

Introduction and objective: Hyperthyroidism is more common in patients with type 2 diabetes mellitus (T2DM) than in those without diabetes. Excess circulating thyroid hormones in hyperthyroidism are associated with poor glycemic control, including hyperglycemia and insulinopenia. This study aimed to determine the association between the serum glycated hemoglobin (HbA1c) and thyroid hormonal profile (FT3, FT4, TSH) in Type 2 diabetic patients.

Methodology: A cross-sectional and case control study examined HbA1c, FT3, FT4 and TSH in 189 Type 2 diabetic patients with good and poor glycemic status, analyzed the associations of these biomarkers for predicting hyperthyroidism using Cox proportional hazard and support vector machine analyses. The methods are conducted following the manufacturer's instructions, spectrophotometric assays are used to measure HbA1c and FBG, while electro chemiluminescent assays are used to measure TSH, FT3, and FT4.

Results: This study was conducted on 97 Type 2 diabetic patients with poor glycemic status compared to 92 good glycemic status patients. The age range of participants is between 21 to 72 years and classified according to WHO age group classification into three age categories, young adults (21-30), middle-aged adults (31-45), old-aged adults (>45) and the duration of the disease is between (4-15) years. FBG (p=0.001), HbA1c (p=0.016), TSH (p=0.009), FT3 (p=0.048), and FT4 (p=0.038) results among Type 2 diabetic patients revealed significant differences between the means of good and poor glycemic state (P<0.05). The correlation between thyroid markers, glycemic parameters and the diabetes duration, revealed significant moderate a negative correlation between TSH and FBG (R=-0.34, p=0.001), HbA1c (R=-0.27, p=0.02), and diabetes duration (R=-0.21, p=0.036), The scatter matrix plot showed strong a positive correlation between FT3 and FBG (R=0.54, p=0.03), HbA1c (R=0.36, p=0.004), and the diabetes duration (R=0.41, p=0.05), FT4 was also strong positively correlated with FBG (R=0.46, p=0.029), HbA1c (R=0.33, p=0.028), and the diabetes duration (R=0.39, p=0.048), indicated that increased FT3 and FT4 levels are associated with poor glycemic status and longer diabetes duration.

Conclusion: Concluded from this study, well-controlled Type 2 Diabetes reduced the risk of hyperthyroidism, relatively high HbA1c and low TSH levels may increase the risk of hyperthyroidism; therefore, the combination of these indicators can serve as a biomarker for identifying healthy individuals from those who would later develop hyperthyroidism.