TSH-Lowering Effect of Metformin in Type 2 Diabetic Patients
Open accessAbstract
OBJECTIVE: To assess the interplay between metformin treatment and thyroid function in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: The acute and long-term effects of metformin on thyroid axis hormones were assessed in diabetic patients with primary hypothyroidism who were either untreated or treated with levothyroxine (L-T4), as well as in diabetic patients with normal thyroid function. RESULTS: No acute changes were found in 11 patients with treated hypothyroidism. After 1 year of metformin administration, a significant thyrotropin (TSH) decrease (P < 0.001) was observed in diabetic subjects with hypothyroidism who were either treated (n = 29; from 2.37 +/- 1.17 to 1.41 +/- 1.21 mIU/l) or untreated (n = 18; 4.5 +/- 0.37 vs. 2.93 +/- 1.48) with L-T4, but not in 54 euthyroid subjects. No significant change in free T4 (FT4) was observed in any group. CONCLUSIONS: Metformin administration influences TSH without change of FT4 in patients with type 2 diabetes and concomitant hypothyroidism. The need for reevaluation of thyroid function in these patients within 6-12 months after starting metformin is indicated.
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
After chronic administration of metformin, FT4 was unchanged and TSH decreased in L-T4-treated or L-T4-untreated hypothyroid diabetics, but not in euthyroid subjects.
“After its chronic administration, FT4 was unchanged and TSH decreased in L-T4-treated or L-T4-untreated hypothyroid diabetics, but not in euthyroid subjects (86).”
From L-T4 therapy in the presence of pharmacological interferents (2020) · cites this paper as [86]
Metformin reduces TSH with no change in FT4 in treated or untreated hypothyroid patients.
“Metformin, the most commonly prescribed pharmacologic treatment for type 2 diabetes, reduces TSH with no change in FT4 in treated or untreated hypothyroid patients [29] or in patients with benign thyroid nodules [30].”
From Challenges in Interpreting Thyroid Stimulating Hormone Results in the Diagnosis of Thyroid Dysfunction (2019) · cites this paper as [29]
Metformin significantly decreases TSH without reciprocal changes in any thyroid function parameter in hypothyroid diabetic patients, but not in euthyroid ones.
“A significant decrease in TSH (P < 0.001) without reciprocal changes in any thyroid function parameter in diabetic patients had also been reported but only in hypothyroid subjects, not in euthyroid ones [113].”
From Metformin: An Old But Still the Best Treatment for Type 2 Diabetes (2013) · cites this paper as [113]
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Cites
Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus
The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus* (2002) · Diabetes Care · doi:10.2337/diacare.25.2007.s5 · Cited by 10,320 · see citing works
Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus
The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (1997) · Diabetes Care · doi:10.2337/diacare.20.7.1183 · Cited by 6,220 · see citing works
Wulffelé, M. G., Kooy, A., Lehert, P., Bets, D., Ogterop, J. C., van der Burg, B. B., Donker, A. J. M., & Stehouwer, C. D. A. (2003) · Journal of Internal Medicine · doi:10.1046/j.1365-2796.2003.01213.x · Cited by 243 · see citing works
Thyrotropin Suppression by Metformin
Vigersky, R. A., Filmore-Nassar, A., & Glass, A. R. (2006) · The Journal of Clinical Endocrinology & Metabolism · doi:10.1210/jc.2005-1210 · Cited by 174 · see citing works
Drug Interactions of Clinical Importance with Antihyperglycaemic Agents
Scheen, A. J. (2005) · Drug Safety · doi:10.2165/00002018-200528070-00004 · Cited by 147 · see citing works
Chubb, S. A. P., Davis, W. A., Inman, Z., & Davis, T. M. E. (2005) · Clinical Endocrinology · doi:10.1111/j.1365-2265.2005.02246.x · Cited by 143 · see citing works
Schwartz, S. L., Fonseca, V. A., Berner, B., Cramer, M., Chiang, Y.-K., & Lewin, A. J. (2006) · Diabetes Care · doi:10.2337/diacare.29.04.06.dc05-1967 · Cited by 129 · see citing works
Isidro, M. L., Penín, M. A., Nemiña, R., & Cordido, F. (2007) · Endocrine · doi:10.1007/s12020-007-9012-3 · Cited by 93 · see citing works
Approaches to Treatment of Type 2 Diabetes
Bloomgarden, Z. T. (2008) · Diabetes Care · doi:10.2337/dc08-zb08 · Cited by 18 · see citing works
Flagged first, then by citations
Cited by
Sorted by citations
Thyroid dysfunction and diabetes mellitus: two closely associated disorders
Biondi, B., Kahaly, G. J., & Robertson, R. P. (2019) · Endocrine Reviews · doi:10.1210/er.2018-00163 · Cited by 598 · see citing works
Metformin: An Old But Still the Best Treatment for Type 2 Diabetes
Rojas, L. B. A., & Gomes, M. B. (2013) · Diabetology & Metabolic Syndrome · doi:10.1186/1758-5996-5-6 · Cited by 567 · see citing works
The relationship between type 2 diabetes mellitus and related thyroid diseases
Wang, C. (2013) · Journal of Diabetes Research · doi:10.1155/2013/390534 · Cited by 273 · see citing works
Treatment with thyroid hormone
Biondi, B., & Wartofsky, L. (2014) · Endocrine Reviews · doi:10.1210/er.2013-1083 · Cited by 259 · see citing works
Subclinical hypothyroidism and type 2 diabetes: A systematic review and meta-analysis
Han, C., He, X., Xia, X., Li, Y., Shi, X., Shan, Z., & Teng, W. (2015) · PLoS ONE · doi:10.1371/journal.pone.0135233 · Cited by 258 · see citing works
Drugs that suppress TSH or cause central hypothyroidism
Haugen, B. R. (2009) · Best Practice & Research Clinical Endocrinology & Metabolism · doi:10.1016/j.beem.2009.08.003 · Cited by 252 · see citing works
The interface between thyroid and diabetes mellitus
Duntas, L. H., Orgiazzi, J., & Brabant, G. (2011) · Clinical Endocrinology · doi:10.1111/j.1365-2265.2011.04029.x · Cited by 247 · see citing works
Effects of treatment with metformin on TSH levels: a meta-analysis of literature studies
Lupoli, R., Di Minno, A., Tortora, A., Ambrosino, P., Arianna Lupoli, G., & Di Minno, M. N. D. (2014) · The Journal of Clinical Endocrinology & Metabolism · doi:10.1210/jc.2013-2965 · Cited by 102 · see citing works
Razvi, S., Bhana, S., & Mrabeti, S. (2019) · Journal of Thyroid Research · doi:10.1155/2019/4106816 · Cited by 90 · see citing works
“Metformin, the most commonly prescribed pharmacologic treatment for type 2 diabetes, reduces TSH with no change in FT4 in treated or untreated hypothyroid patients [29] or in patients with benign thyroid nodules [30].”
BackgroundDiabetes and thyroid disorders
Brenta, G. (2010) · The British Journal of Diabetes & Vascular Disease · doi:10.1177/1474651410371321 · Cited by 58 · see citing works
Ward, L. S. (2010) · Arquivos Brasileiros de Endocrinologia & Metabologia · doi:10.1590/s0004-27302010000500002 · Cited by 53 · see citing works
Central hypothyroidism in adults: better understanding for better care
Grunenwald, S., & Caron, P. (2015) · Pituitary · doi:10.1007/s11102-014-0559-8 · Cited by 35 · see citing works
Pirola, I., Gandossi, E., Brancato, D., Marini, F., Cristiano, A., Delbarba, A., Agosti, B., Castellano, M., & Cappelli, C. (2018) · Journal of Endocrinological Investigation · doi:10.1007/s40618-018-0867-3 · Cited by 21 · see citing works
Self-citationAdministration and pharmacokinetics of levothyroxine
Lipp, H.-P. (2021) · 70 Years of Levothyroxine · doi:10.1007/978-3-030-63277-9_2 · Cited by 18 · see citing works
Metformin does not suppress serum thyrotropin by increasing levothyroxine absorption
Al-Alusi, M. A., Du, L., Li, N., Yeh, M. W., He, X., Braverman, L. E., & Leung, A. M. (2015) · Thyroid · doi:10.1089/thy.2015.0211 · Cited by 14 · see citing works
L-T4 therapy in the presence of pharmacological interferents
Benvenga, S. (2020) · Frontiers in Endocrinology · doi:10.3389/fendo.2020.607446 · Cited by 13 · see citing works
- Authors
- Cappelli, C., Rotondi, M., Pirola, I., Agosti, B., Gandossi, E., Valentini, U., De Martino, E., Cimino, A., Chiovato, L., Agabiti-Rosei, E., & Castellano, M.
- Affiliations
- University of Brescia (IT)
- University of Pavia (IT)
- Azienda Socio Sanitaria Territoriale degli Spedali Civili di Brescia (IT)
- Internal Medicine and Endocrinology Unit, Department of Medical and Surgical Sciences, University of Brescia, Brescia, Italy;
- Corresponding author
- Cappelli, Carlo
- ORCID
- Venue
- Diabetes Care
- Publisher
- American Diabetes Association
- Published
- 2009-06-05
- Volume
- 32
- Issue
- 9
- Pages
- 1589-1590
- ISSN
- 0149-5992 (ISSN-L)
- 1935-5548
- PMC
- PMC2732148
- OpenAlex
- W2170285171
- Cited by
- 173
- References
- 9
- Citations by year
- 2026: 3 · 2025: 7 · 2024: 7 · 2023: 11 · 2022: 18 · 2021: 7 · 2020: 12 · 2019: 12 · 2018: 9 · 2017: 13 · 2016: 11 · 2015: 8 · 2014: 15 · 2013: 14 · 2012: 12
- FWCI
- 6.31
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Diabetes Care (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- Institutional Research Information System (Università degli Studi di Brescia) (submittedVersion, other-oa)
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Treatment and Management
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Management and Research
- Keywords
- metformin, thyroid-stimulating hormone, type 2 diabetes, hypothyroidism, levothyroxine, thyroid function, free thyroxine, thyroid function monitoring
- MeSH terms
- Diabetes Mellitus, Type 2, Humans, Hypoglycemic Agents, Hypothyroidism, Metformin, Thyroid Diseases, Thyrotropin, Thyroxine, Time
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
