Diabetes mellitus and thyroid disease are common endocrine disorders in the general population. To investigate the association between thyroid dysfunction, thyroid autoimmunity and Saudi type 2 diabetics, a random sample of 100 Saudi type 2 diabetics and 100 age- and sex-matched controls were studied. The mean age was 54 years for diabetics and 55 years for controls while the male:female ratios were 1:1.6 and 1:14 respectively. GAD65ab were found in 26% diabetics and 2% controls (p=0.001). Thyroid autoimmunity were detected in 10% diabetics vs. 5% controls (p=0.05), while thyroid dysfunction was found in 16% and 7% respectively (p=0.03). In GAD65ab-positive diabetics, thyroid autoimmunity was observed in 27% vs. 4% GAD65ab-negative diabetics (p=0.02) and thyroid dysfunction was reported in 42% and 7% respectively. We conclude that thyroid dysfunction and autoimmunity are common in Saudi type 2 diabetics. Further studies are needed on the cost effectiveness of thyroid screening in diabetics.