The effect of Metformin treatment in obese insulin-resistant patients with euthyroid goiter.

Objective The study's objective was to evaluate the thyroid parameters in obese insulin-resistant patients with euthyroid diffuse or nodular goiter, following Metformin treatment. Patients and methods The study was experimental, open, and prospective. Fifty-three patients aged 18-68 were enrolled for two years. Obese insulin-resistant patients (cut-off Homeostasis-Model-Assessment of Insulin Resistance-HOMA-IR ≥ 2.5) with euthyroid nodular/diffuse goiter were included. Subjects with diabetes, hypo-/hyper-thyroidism, autoimmune thyroiditis, psychiatric disorders, liver or heart failure were excluded. Patients were randomly assigned to one of the following treatment: Metformin 1000 mg/day + Levothyroxine 25 µg/day (M + LT4 group) and only Levothyroxine 25 µg/day (LT4 group). Thyroid and metabolic parameters' evolution was investigated over six months. Results The two groups were comparable at baseline (p ≥ 0.10). TSH, waist/hip ratio (WHR), visceral fat thickness (VFT), insulin, and HOMA-IR decreased significantly more in M + LT4 group compared to LT4 group. TSH decrease correlated with WHR reduction (p = 0.002) only in M + LT4 group. Moreover, the multivariate regression analysis revealed that insulin's and HOMA-IR levels' decrease was an independent factor associated with FT4's increase (p = 0.031, p = 0.033) just in M + LT4 group. No other independent association between the evolution (Δ) of TSH, thyroid volume (TTV), thyroid nodules-maximum diameter (TN-MD), and metabolic parameters was found. In addition, no significant threshold between groups was reached when ΔFT4, ΔTTV, ΔTN-MD were compared (p > 0.07), although their significant improvement was recorded between the baseline and the follow-up moment in each group (p < 0.003). Conclusion Metformin added to obese insulin-resistant patients treated with Levothyroxine for diffuse/nodular goiter determined a significant decrease in TSH and metabolic parameters, compared to those treated with Levothyroxine alone, but no significant difference regarding thyroid morphology after 6 months.

Thyroid disorders in obese patients. Does insulin resistance make a difference?

ABSTRACT Objective: The aim of this study was to evaluate the association between insulin resistance and thyroid pathology in obese patients, and compare the results between insulin-resistant and noninsulin-resistant patients. Subjects and methods: Obese/nondiabetic patients, aged 18-70 years, attending the outpatient endocrinology service for 2 years were consecutively included. We evaluated the patients' fasting plasma glucose, insulin, homeostasis model assessment of insulin resistance index (HOMA-IR), thyroid-stimulating hormone (TSH), free thyroxine (FT4), antithyroperoxidase antibodies (TPO-Ab), antithyroglobulin antibodies (Tg-Ab), and thyroid ultrasound. Results: We included 82 patients with a mean age 44.21 ± 12.67 years. The thyroid disorders encountered and their prevalences were: hypothyroidism (14.6%, 95% confidence interval [CI] 8.6-23.8%), hyperthyroidism (1.2%, 95% CI 2.0-6.6%), goiter (28.0%, 95% CI 19.5-3.6%), thyroid nodules (35.4%, 95% CI 25.9-46.2%), and Hashimoto's thyroiditis (32.9%, 95% CI 23.7-43.7%). HOMA-IR correlated positively with TSH levels (r = 0.24, p = 0.028), and this correlation remained after adjustment for body mass index (BMI), waist/hip ratio (WHR), serum cortisol, subcutaneous fat thickness (SFT), visceral fat thickness (VFT), triglycerides, γ-glutamyl transpeptidase (GGT), and alanine aminotransferase (ALT) in multivariate regression analysis (b = 0.207, 95% CI, 0.09-0.385, p = 0.023). TSH levels were significantly higher in patients with HOMA-IR ≥ 2.5 than in those with HOMA-IR < 2.5 (2.03 μIU/mL, interquartile range [IQR] 1.59-2.69 μIU/mL) versus 1.59 μIU/mL, IQR 0.94-2.26 μIU/mL, p = 0.023). Conclusions: The most prevalent thyroid disorder in patients attending our endocrinology clinic for investigation of obesity was thyroid nodules. One in seven patients had hypothyroidism. Our findings suggest that TSH levels correlate with insulin resistance in obese patients.

Thyroid disorders in obese patients. Does insulin resistance make a difference?

OBJECTIVE: The aim of this study was to evaluate the association between insulin resistance and thyroid pathology in obese patients, and compare the results between insulin-resistant and noninsulin-resistant patients. SUBJECTS AND METHODS: Obese/nondiabetic patients, aged 18-70 years, attending the outpatient endocrinology service for 2 years were consecutively included. We evaluated the patients' fasting plasma glucose, insulin, homeostasis model assessment of insulin resistance index (HOMA-IR), thyroid-stimulating hormone (TSH), free thyroxine (FT4), antithyroperoxidase antibodies (TPO-Ab), antithyroglobulin antibodies (Tg-Ab), and thyroid ultrasound. RESULTS: We included 82 patients with a mean age 44.21 ± 12.67 years. The thyroid disorders encountered and their prevalences were: hypothyroidism (14.6%, 95% confidence interval [CI] 8.6-23.8%), hyperthyroidism (1.2%, 95% CI 2.0-6.6%), goiter (28.0%, 95% CI 19.5-3.6%), thyroid nodules (35.4%, 95% CI 25.9-46.2%), and Hashimoto's thyroiditis (32.9%, 95% CI 23.7-43.7%). HOMA-IR correlated positively with TSH levels (r = 0.24, p = 0.028), and this correlation remained after adjustment for body mass index (BMI), waist/hip ratio (WHR), serum cortisol, subcutaneous fat thickness (SFT), visceral fat thickness (VFT), triglycerides, γ-glutamyl transpeptidase (GGT), and alanine aminotransferase (ALT) in multivariate regression analysis (b = 0.207, 95% CI, 0.09-0.385, p = 0.023). TSH levels were significantly higher in patients with HOMA-IR ≥ 2.5 than in those with HOMA-IR < 2.5 (2.03 µIU/mL, interquartile range [IQR] 1.59-2.69 µIU/mL) versus 1.59 µIU/mL, IQR 0.94-2.26 µIU/mL, p = 0.023). CONCLUSIONS: The most prevalent thyroid disorder in patients attending our endocrinology clinic for investigation of obesity was thyroid nodules. One in seven patients had hypothyroidism. Our findings suggest that TSH levels correlate with insulin resistance in obese patients.