Table 4:

Crude and adjusted hazard ratios for suppressed thyroid-stimulating hormone levels (< 0.1 mIU/L) associated with the use metformin monotherapy, compared with sulfonylurea monotherapy, in patients with treated hypothyroidism or euthyroidism and type 2 diabetes

VariableNo. events of suppressed TSH levelsPerson-years of exposureIncidence rate, per 1000 person-years (95% CI)Crude HRAdjusted HR* (95% CI)
Patients with treated hypothyroidism, n = 5689
Sulfonylurea, n = 7621850335.8 (21.2–56.6)1.001.00 (reference)
Metformin, n = 49271303 63335.8 (29.9–42.5)1.050.99 (0.57–1.72)
Euthyroid patients, n = 59 937
Sulfonylurea, n = 7980128 5761.4 (0.7–2.4)1.001.00 (reference)
Metformin, n = 51 9577563 0471.2 (0.9–1.5)0.851.03 (0.52–2.03)
  • Note: CI = confidence interval, HR = hazard ratio, TSH = thyroid stimulating hormone.

  • * Adjusted for age, sex, year of cohort entry, body mass index, smoking, excessive alcohol use (i.e., alcohol-related disorders such as alcoholism, alcoholic cirrhosis, alcoholic hepatitis and hepatic failure), hemoglobin A1C, duration of diabetes, and use of lithium, amiodarone and glucocorticoids.