INS and Alzheimer disease: In Cox regression analysis, compared to T2DM patients without both pioglitazone and insulin, T2DM patients receiving both pioglitazone and insulin had a higher risk of developing AD (aHR = 2.004, 95% CI = 1.702–2.498, p < 0.05, Fig. 2 and Supplementary Table S3), T2DM patients receiving pioglitazone alone had a higher risk of developing AD (aHR = 1.596, 95% CI = 1.398–1.803, p < 0.05, Fig. 2), and T2DM patients receiving insulin alone had a higher risk of developing AD (aHR = 1.365, 95% CI = 1.125–1.572, p < 0.05, Fig. 2 and Supplementary Table S3).