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Thyreotropin levels in diabetic patients on metformin treatment

Cappelli C, Rotondi M, Pirola I, Agosti B, Formenti A, Zarra E, Valentini U, Leporati P et al.

European journal of endocrinology, 2012

203 participants · 88 citations

Abstract

OBJECTIVE: A retrospective study to evaluate the changes in TSH concentrations in diabetic patients treated or not treated with metformin and/or L-thyroxine (L-T(4)).

METHODS: Three hundred and ninety three euthyroid diabetic patients were divided into three groups on the basis of metformin and/or L-T(4) treatment: Group (M-/L-), 119 subjects never treated with metformin and L-T(4); Group (M+/L-), 203 subjects who started metformin treatment at recruitment; and Group (M+/L+), 71 patients on L-T(4) who started metformin recruitment.

RESULTS: The effect of metformin on serum TSH concentrations was analyzed in relation to the basal value of TSH (below 2.5 mIU/L (Q1) or between 2.51 and 4.5 mIU/L (Q2)). In patients of group M+/L+, TSH significantly decreased independently from the basal level (Q1, from 1.450.53 to 1.011.12 mU/L (P=0.037); Q2, from 3.600.53 to 1.910.89 mU/L (P<0.0001)). In M+/L group, the decrease in TSH was significant only in those patients with a basal high-normal serum TSH (Q2: from 3.24±0.51 to 2.27±1.28 mU/l (P=0.004)); in M-/L- patients, no significant changes in TSH levels were observed. In patients of group M+/L showing high-normal basal TSH levels, a significant decrease in TSH was observed independently from the presence or absence of thyroid peroxidase antibodies (ABTPO; Q2 ABTPO +: from 3.38±0.48 to 1.87±1.08 mU/l (P<0.001); Q2 AbTPO -: from 3.21±0.52 to 2.34±1.31 mU/l (P<0.001)).

CONCLUSIONS: These data strengthen the known TSH-lowering effect of…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 203 participants or records.

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