This study was planned to investigate the relationships between serum thyroid hormone and cortisol levels in patients with type II diabetes mellitus with different clinical status. Thirteen patients without complications, 31 with chronic complications, 22 with acute complications and 11 control subjects were studied and results compared. Serum T4, fT4 and TSH levels did not differ significantly from the control group. Free T3 levels were significantly lower in all diabetic groups than the control group. Free T3 and T3 levels were significantly lower in patients with acute complications than the other three groups. There were negative correlations between fasting blood glucose and T3 and fT3 levels but a positive correlation with cortisol.