INS and depressive disorder: Several potential pathways between T2D and depression have been widely accepted, one of which is that the use of diabetes drugs will increase the incidence rate of depression, including the use of insulin, sulfonylurea drugs, and high-dose metformin (38). A study (25) found that T2D patients had a higher risk of developing MD, and as the number of risk factors within the recommended target range increased, the additional risk of developing MD decreased, which may be related to unhealthy lifestyles.