metformin and thyroid in obese insulin-resistant patients

What is it about?

Metformin is an insulin-sensitizing, antidiabetic agent, commonly used in the treatment of patients with prediabetes/type2 diabetes mellitus. Its impact on thyroid morpho-function in insulin-resistant patients remains a reason of controversy. The objective of our research was to investigate the effect of Metformin on thyroid morpho-functional parameters in obese, insulin-resistant, non-diabetic patients who associate euthyroid diffuse/nodular goiter, as the data reported for this category of patients are few and unclear. We have associated Levothyroxine suppressive therapy to see if combined therapy (Metformin and Levothyroxine) has a stronger inhibitive effect on TSH and/or on the evolution of the nodular goiter as compared to the singular Levothyroxine treatment.

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Why is it important?

Metformin added to obese insulin-resistant patients treated with Levothyroxine for euthyroid diffuse/nodular goiter produced a significant decrease of TSH and of the metabolic parameters, higher than in the patients treated with Levothyroxine alone. Moreover, the reduction of visceral obesity (WHR) correlated significantly with TSH decrease and with the follow-up thyroid volume only in Metformin + Levothyroxine treated group. The statistical significance threshold was not reached when comparing the evolution of thyroid volume and thyroid nodule-maximum diameter of the two groups after 6 months of treatment, although there were significant decreases of these parameters between the initial and the final point in each group. Furthermore, the decrease of thyroid volume correlated significantly with the reduction of visceral adiposity and insulin levels for both groups.

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