This study was undertaken to assess the thyroid profile of diabetes mellitus (DM) patients and patients with some associated complications in the Edo state, Nigeria. Blood samples from 267 subjects, consisting of 164 diabetic patients (24 type 1 DM and 140 type 2 DM) and 103 nondia- betic apparently healthy individuals (as controls), were analyzed. The thyroid stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) levels were determined using the enzyme linked immunosorbent assay (ELISA). From the result obtained, the T3 level was found signifi- cantly (p < 0.05) higher in diabetic-nephropathy (D-NEPHR) patients than the control subjects, while the TSH and T4 levels of D-NEPHR were insignificantly (p > 0.05) higher than those of the control group. The mean TSH level was significantly (p < 0.05) lower in diabetic hypertensive patients when compared with the control group, while the plasma T3 level was significantly (p < 0.05) higher in diabetic hypertensive patients when compared with the control group. There was no significant difference (p > 0.05) in the mean value of T4 of diabetic hypertensive patients when compared with the control subjects. The mean plasma T3 and T4 were significantly (p < 0.05) higher in diabetic neuropathy (D-NEUR) patients than those of control subjects. There were no significant (p > 0.05) differences in the mean plasma TSH level of D-NEUR patients when compared with those of control subjects. The mean plasma T3and T4 levels of diabetic patients with coronary heart disease (DM-CHD) were significantly (p < 0.05) higher than those of control subjects while the mean plasma TSH level of DM-CHD was significantly (p < 0.05) lower than that of control subjects. No significant (p > 0.05) difference in the mean plasma TSH, T4, and T3 levels of diabetic retinopathy subjects when compared with those of control subjects was obtained.