Metformin-induced thyrotropin suppression is not associated with cardiac effects

Carlo Cappelli, Mario Rotondi, Ilenia Pirola, Barbara Agosti, Ana Maria Formenti, Pasquale De Cata, Massimo Salvetti, Luca Chiovato, Maurizio Castellano

Research output: Contribution to journalArticlepeer-review


Objective: Metformin treatment may induce a decrease/suppression in serum TSH levels, mimicking sub-clinical hyperthyroidism (SHT). The aim of the present study was to retrospectively evaluate changes in several electrocardiographic indices in euthyroid subjects with diabetes who, after starting metformin treatment, developed a low serum TSH as compared to patients with SHT resulting from an underlying thyroid disease or TSH suppressive treatment with L-thyroxine. Design: Heart rate, P wave duration, P wave dispersion, QTmax, QTmin and QT-dispersion were assessed in 23 patients with diabetes treated with metformin before and after 6 months of TS H-suppression and in 31 control patients with SHT. Results: No significant changes in electrocardiographic parameters were observed from baseline to the TSH-suppression measurement. A significant difference in P wave duration (102.9±7.4 vs. 92.1±5.8 ms, p

Original languageEnglish
Pages (from-to)252-258
Number of pages7
Issue number2
Publication statusPublished - 2014


  • Atrial fibrillation
  • Metformin
  • Sub-clinical hyperthyroidism

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Medicine(all)


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