Background: Thyroid diseases and diabetes mellitus are the two most common endocrine disorders encountered in clinical practice. Hyper– and hypothyroidism have been associated with insulin resistance, which has been reported to be the major cause of impaired glucose metabolism in type II DM^.

Objective:  The main aim of this study to investigate the prevalence of Hypothyroidism among patient with type two diabetes mellitus in security forces hospital, Riyadh.

Methods: A retrospective cross–sectional study was done on patients who diagnosed with type II DM and regularly attended the diabetic center care at security forces hospital, Riyadh, Saudi Arabia.

Results: Out of 300 randomly selected type 2 diabetic patients with hypothyroidism; 82% have TSH level ranged between 0.5 to 5.0 µIU/dl (group 1) and 13% have TSH level > 5.0 µIU/dl (group 2). In addition, there was a statistically significant association between HbA1C level and type of treatment received by our population but fasting blood glucose level was not significant. Regarding the TSH level, out of 300 patients; 9.5% were diagnosed normal and 90.5% were diagnosed abnormal regarding to the TSH level.

Conclusion: In our population, the prevalence of female diabetic patients with hypothyroidism was 1.8 times higher than diabetic male. The prevalence of abnormal diagnosed level of TSH was 9.5 times higher than normal level.