Table 2.
Association between thyroid function and the risk of incident prediabetes and diabetes
| Thyroid function measurements | HR (95 % CI) Model 1 | HR (95 % CI) Model 2 | Incident cases | Total participants |
|---|---|---|---|---|
| Incident Diabetes | ||||
| Full range of measurement | ||||
| TSH mIU/L | 1.09 (1.06–1.12) | 1.06 (1.00–1.13) | 798 | 8447 |
| Free T4 pmol/L | 0.96 (0.93–0.99) | 0.96 (0.93–0.99) | 797 | 8446 |
| Normal TSH and FT4 values | ||||
| TSH mIU/L | 1.16 (1.04–1.30) | 1.14 (1.02–1.27) | 685 | 7188 |
| Free T4 pmol/L | 0.96 (0.92–0.99) | 0.94 (0.90–0.98) | 685 | 7188 |
| Progression from prediabetes to diabetes | ||||
| Full range of measurement | ||||
| TSH mIU/L | 1.17 (1.07–1.27) | 1.13 (1.03–1.24) | 412 | 1337 |
| Free T4 pmol/L | 0.92 (0.89–0.97) | 0.93 (0.89–0.98) | 411 | 1336 |
| Normal TSH and FT4 values | ||||
| TSH mIU/L | 1.26 (1.08–1.47) | 1.21 (1.04–1.41) | 358 | 1137 |
| Free T4 pmol/L | 0.90 (0.85–0.95) | 0.91 (0.86–0.97) | 358 | 1137 |
Model 1: adjusted for sex, age, smoking, fasting serum glucose levels and cohort
Model 2: adjusted for sex, age, smoking, cohort, fasting serum glucose levels, fasting serum insulin measurements, systolic blood pressure, diastolic blood pressure, blood pressure lowering medication, HDL cholesterol, and body mass index
Normal range of TSH is defined by 0.4–4.0 mIU/L and normal range FT4 is defined by 11–25 pmol/L and participants not using levothyroxine
Results are presented as HR per doubling of TSH on average and per one increase in pmol/L of FT4
CI confidence interval, FT4 free thyroxine, HR hazard ratio, TSH thyroid-stimulating hormone