INS and diabetes mellitus: Consistent with a younger age, diabetes was also less frequent amongst the SUD group 1.37% vs. 6.11% (Student's t = -2.08, df = 171.49, P = 0.0381), but the use of insulin was no different (4.11% vs. 4.58%, Student's t = -0.16, df = 270.33, P = 0.87).