To cope the high glycemic variability (GV) is crucial in the management of multiple daily insulin (MDI) in diabetes. We compared the effect of low dose metformin 750mg/d adding vildagliptin 100mg/d (DPP4+LMET) or the high dose metformin 1500mg/d (HMET), in type 2 diabetes (T2D) with MDI, evaluating GV by continuous glucose monitoring (CGM). Single center, open-label, 12 weeks - 2 period crossover design. Twenty T2D with inadequately controlled (7.0% <HbA1c ≦9.0%) with MDI + LMET were enrolled. Primary endpoints were GV and hypoglycemia derived from CGM performed after each 12 weeks treatment periods. There was no significant difference in HbA1c, body weight changes, total daily dose of insulin. DPP4+LMET compared to the HMET, significantly reduced the calculated GV value, mean (7.15±1.3 vs 7.82±1.6, p<0.05), standard deviation (1.78±0.55 vs 2.27±1.11, p=0.03), continuous overlapping net glycemic action (6.44±1.28 vs 7.12±1.69, p<0.05), J-Index (26.7±11.0 vs 34.9±19.8, p<0.05), high blood glucose index (3.01±1.96 vs. 6.73±4.85, p=0.02), and mean amplitude of glycemic excursions (4.53±1.35 vs 5.50±2.34, p=0.03). The GV metrics with hypoglycemia and nocturnal hypoglycemia were not significantly different. DPP4+LMET decreased GV associated with hyperglycemia. Adding DPP4 inhibitor to the lower dose of metformin is an alternative approach to the stable GV in MDI.