INS and Alzheimer disease: Compared to patients without both insulin and pioglitazone, higher cumulative risk of developing AD was found in patients receiving both insulin and pioglitazone (aHR = 2.004, 95% CI = 1.702–2.498), pioglitazone alone (aHR = 1.596, 95% CI = 1.398–1.803), and insulin alone (aHR = 1.365, 95% CI = 1.125–1.572), respectively (all p < 0.05).