Incretin levels in patients with hypothyrody and the evaluation of incretin level alterations with treatment

Thyroid hormones may affect carbonhydrate metabolism and insulin secretion. The incretin effect is responsible from most of release of insulin after oral food intake. Additionally incretin hormones may have role in the insulin secretion, insulin resistance and glucose metabolism effects of thyroid hormones. In our study we aimed to determine whether incretine hormones have role in the thyroid hormones effect of insulin resistance and glucose metabolism. In this study we have 26 people in two groups consisting 13 people which have hypothyroid patients and healthy controls separately; the two groups compared with each other. Also hypothyroid patients treated to be euthyroid and the datas are compared between hypothyroid and euthyroid state. The 75 g oral glucose tolerance test is performed in the patients. Levels of glucose, GLP-1, GIP, insulin and c-peptide levels were measured in 0, 30, 60, 90 and 120th minutes. In hypothyroid group the waist circumferences are decreased after initiation to euthyroid state with treatment (p=0,026). There were no significant difference between hypothyroid and control groups in the levels of insulin, c-peptide and glucose during the OGTT. The 60th minute glucose and c-peptide levels are decreased in hypothyroid group after initiation of euthyroid state with treatment (p=0,05, p=0,046, respectively). There was no difference GLP-1 responses during OGTT between the hypothyroid and the control group. In hypothyroid group peak GLP-1 levels determined at 90th minute; in the control group peak GLP-1 value was reached after 30 minutes. There was no difference GIP response during OGTT between the hypothyroidism and control groups. In hypothyroid group peak GIP levels determined at 60th minute; in the control group peak GIP value was reached at 90th minutes. In hypothyroid group before the treatment and after the treatment providing euthyroidy there was no difference between the groups response to GLP-1 during OGTT. In hypothyroid group before the treatment the peak GLP-1 level was determined in 90th minute and after the treatment the peak GLP-1 level was determined in 30th minute. In hypothyroid group before and after treatment providing euthyroidy; there was no difference to GIP responses during OGTT between the groups. In hypothyroid group peak GIP level was reached at 60th minute and after the treatment providing euthyroidy peak GIP level was reached at 30th minute. In conclusion; incretin hormones especially peak response of the incretin system is significantly affected in patients with hypothroidism. Significant changes in incretin system were found by correcting hypothyroidism Key words: Hypothyroid, OGTT, incretin, GLP-1, GIP