Muhammad Farooq, Arshad Ali, Nayyer-ul Islam, Asad Qamar, Mohammad Yousuf-ul Islam.
Sub-clinical hypothyroidism in diabetes and effect of metformin on thyroid stimulating hormone.
Pak J Surg Jan ;34(3):234-40.

Introduction: Patients with type 2 diabetes mellitus (DM) are associated withelevated thyroid stimulating hormone (TSH)level. Metformin is considered as standard therapy in type 2 DM and it alters TSH levels. Objective: To see the effect of metformin treatment on thyroid function in patients with type 2 diabetes mellitus. Design: Interventional Clinical Trial using convenience sampling Place and Study Duration:the study was conducted in Dallah Hospital, Riyadh, Kingdom of Saudia Arabia. It lasted for an year (from April 2014 to June 2015). Material and Methods: Two hundred and seventy one patients with type 2 DM were given metformin 2000 mg/day for approximately 24 weeks. The thyroid function [TSH, free thyroxin (FT4) and total thyroxin (TT4)] done at baseline, after 12 weeks and 24 weeks of metformintherapy. Two groups, the euthyroid group and SHT group were analyzed and compared. Results: Among 271 patients, 15.5% (42) were classified in SHT group, whereas 84.5% (229) in euthyroid group. There were no significant diff erences of age and lipid levels between two groups whereas the high BMI, female gender, high FBS and HbA1c were associated with SHT group.the mean baseline TSH was 2.94+2.36 mIU/L in all subjects, 7.54+2.69 mIU in SHT group whereas 2.10+0.83 in euthyroid group. There was significant reduction in TSH level noted in SHT group after 3 months(p=0.017) and 6 months(p<0.001) of metformin therapy.the mean baseline TT 4 was 9.13+1.59 in all subjects, 8.57+2.10 in SHT group whereas 9.24+1.40 in euthyroid group. The mean baseline FT4 was 1.08+0.24 in all subjects, 1.07+0.35 in SHT group whereas 1.08+0.22 in euthyroid group. Conclusions: the study revealed close association of SHT with type 2 DM. The TSH lowering effect of metformin therapy only evident with SHT. There was no significant change seen in FT4 and TT4 levels.

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