Effects of treatment with L-thyroxin on glucose regulation in patients with subclinical hypothyroidism.

AIMS We examined effects of treatment with 1-thyroxin on glucose regulation in patients with subclinical hypothyroidism. METHODS The study included 100 patients, ages 51.75 +/- 13.23 years, BMI = 27.97 +/- 4.52 kg/m2, with SH (TSH > 4.2 mU/L and with normal level of T3 and T4). Laboratory evaluation included serum free T3, free T4, TSH, thyroid antibodies, TGL, insulin, C-peptide and glucose during OGTT, HbA1c, CRP and level of lipids. Percentile, average and correlation analysis have been utilized in statistical analysis. Twelve patients with SH had GI and 38 patients had DM. All patients were treated with low dose of 1-thyroxin (25-50 ug) and high physical activity. RESULTS After 6 months treatment with 1-thyroxin, patients had normal or limited TSH (5.85 +/- 0.92 vs. 3.54 +/- 0.55 mU/L), level of fasting insulin (114.64 +/- 24.11 vs. 96.44 +/- 17.26 pmol/l) significantly decreased, HbA1c (6.74 +/- 1.01 vs. 6.26 +/- 1.12) decreased as well. The level of CRP significantly decreased as well (2.27 +/- 0.8 vs. 3.32 +/- 1.1 mg/l). The changes were and in level of total cholesterol (5.39 +/- 0.57 vs. 6.10 +/- 0.67 mmol/l), triglyceride levels (1.69 +/- 0.37 vs. 2.22 +/- 0.49 mmol/l), HDL cholesterol (1.16 +/- 0.14 vs. 1.03 +/- 0.15 mmol/l) and LDL cholesterol (3.79 +/- 0.64 vs. 4.37 +/- 0.77 mmol/l). The correlation between TSH and HbA1c was positive and significant (r = 0.46). CONCLUSION The normalization of TSH resulted in decrease of level of fasting insulin, fasting and postprandial glucose, CRP and lipids. Higher CRP associated with fasting hyperinsulinemia before insulin resistance has been evidenced in most patients with SH. These data support an important role of treatment of SH in support of glucose regulation.