PTH and diabetes mellitus: After adjusting for the month of blood collection, sex, age, BMI, smoking status, the extent of physical activity, the use of anti-hypertensive medications, the duration of diabetes, and the levels of total cholesterol, triglycerides, HDL cholesterol, and the log-PTH level (Model 3), the association between HbA1c and 25(OH)D levels remained significant (Q1: 7.47% [7.30–7.63], Q2: 7.25% [7.09–7.40], Q3: 7.17% [7.02–7.32], Q4: 7.19% [7.02–7.35]; p for trend = 0.021, p for between groups = 0.050).