Objective To investigate the related risk factors of type 2 diabetes mellitus combined with hypothyroidism. Methods From Jan 2013 to Jan 2015, 64 patients with type 2 diabetes mellitus combined with hypothyroidism in our hospital were selected as the case group, 128 patients with type 2 diabetes mellitus were randomly selected as the control group. The clinical data of the two groups were collected and analyzed by Logistic regression analysis. Results Single factor non conditional Logistic regression analysis showed that insulin therapy and metformin treatment were protective factors of type 2 diabetes mellitus with hypothyroidism( ■ = 0.195, 0.541. 95% CI = 0.084-0.232, 0.216-0.838 ). Diabetic nephropathy, lipid metabolism disorders, high fibrinogen, smoking history, high HbAlc and TPO-Ab positive were risk factors for type 2 diabetes mellitus combined with hypothyroidism (■ = 8.440, 4.276, 6.678, 6.266, 1.813, 6.131. 95% CI = 3.140-13.467, 1.106-5.978, 2.340-9.015, 2.135-8.249, 1.017-2.826, 2.338-9.059). Multiple factor non conditional Logistic regression analysis found that insulin therapy was a protective factor for type 2 diabetes mellitus with hypothyroidism(■ = 0.198, 95% CI = 0.081-0.246 ). Diabetic nephropathy, smoking history, and TPO-Ab positive were risk factors for type 2 diabetes mellitus combined with hypothyroidism(■ = 8.398, 6.240, 6.080. 95% CI = 3.132-13.514, 2.101-8.568, 2.324-8.942 ). Conclusions Insulin therapy, diabetic nephropathy, smoking history, TPO-Ab positive are associated with type 2 diabetes mellitus combined with hypothyroidism. Type 2 diabetes with diabetes mellitus, smoking history, TPO-Ab positive should be regularly monitor their thyroid function.