Does metformin have a "buffer effect" on serum TSH levels in euthyroid diabetic patients?

Objective: In the last few years a number of studies have found that metformin has a thyrotropin (TSH)-lowering effect in patients with type 2 diabetes (DM2) and that this effect disappears after discontinuation of the drug. Initial studies were carried out in hypothyroid patients on levothyroxine (LT4) treatment. However, this effect was observed only when serum TSH levels were elevated.

The incidence and prevalence of thyroid dysfunction in Europe: a meta-analysis.

Context: Thyroid dysfunction is one of the leading endocrine disorders. Previous data show that about half of the population with thyroid dysfunction remains undiagnosed.

Objective: Our objective was to estimate epidemiologic data on thyroid dysfunction in Europe.