Effect of thyroid hormones on Hyperglycaemia in patients with Type 2 diabetes mellitus

Abstract

Background: Insulin and thyroid hormones are both involved in cellular metabolism and excess or deficit of either of these hormones may result in the functional derangement of the other. Thyroid hormone action has long been recognized as an important determinant of glucose homeostasis. The present study was conducted to find out the correlation between hyperglycaemia and thyroid hormones in patients with T2DM.

Methods: Two hundred subjects with T2DM were enrolled in the study. This included 100 newly diagnosed T2DM cases and 100 patients who were already on follow-up at our hospital. In addition, 100 normal healthy controls were also taken for the study. All subjects were investigated for FPG, HbA1C, FT3, FT4 and TSH.

Results: Out of total 200 patients with T2DM, 161 cases had normal thyroid parameters (group 1), 25 cases had sub-clinical hypothyroidism (group 2), 10 patients were diagnosed with primary hypothyroidism (group 3) and 4 cases had primary hyperthyroidism (group 4). The mean FPG was elevated in group 1(152.5 ± 23.8) and group 4 (173.65 ± 59.3). Mean HbA1C was higher in patients with hyperthyroidism (8.1 ± 2.5). Subjects were further divided into three groups based on the diagnosis of T2DM as newly diagnosed T2DM cases, patients who were on long term follow- up of T2DM and controls. The FPG & HbA1C was significantly higher (p <0.001) in both newly diagnosed T2DM patients & in those cases who were on longterm follow-up. Mean TSH was significantly elevated in long term followup patients with T2DM (7.68 ± 5.75, p < 0.001) and newly diagnosed T2DM cases (5.32 ± 1.54, p<0.001), when compared with controls (3.22 ±1.5, p < 0.001).

Conclusion: We conclude that biochemical screening for thyroid disease is essential in diabetic patients; predominantly in patients whose associated conditions are difficult to accomplish and the possible symptoms of thyroid disease being camouflaged by the diabetic state.