The major aims of DPPOS-3 (2014-2025) take advantage of the long-term randomized exposure of the study cohort to metformin and the aging of the DPPOS cohort. The metformin exposure and high degree of study retention and adherence (~85% of the DPPOS cohort continues to attend annual and mid-year visits) allows DPPOS-3 to examine the long-term effects of metformin on cardiovascular disease (CVD) and cancer outcomes, outcomes of great clinical interest and import.