After propensity score and 1:1 nearest neighbor matching, the variables that significantly yielded selection bias and misunderstanding results were well matched, including age, gender, BMI, HbA1c level, smoking history, lipids, blood pressure, race, education, previous heart failure, previous CVD, sulfonylureas, biguanides, meglitinide, alpha-glucosidase inhibitors, thiazolidinediones, regular insulins and statins. Here, INS is linked to heart failure.