Table I.

Characteristics of various anti-diabetic drugs combined with metformin

Metformin	↓ HbA1c	↓ PPG	Long-term efficacy	↑ Hypo-glycemia	↑ Fluid retention/heart failure	↑Body weight	↑ Bone fractures	Long-term safety	↑ Gastro-intestinal side-effects
Plus sulfonylureas	+++	+	–	+++	–	++	–	+	–
Plus repaglinide	++	++	+	++	–	++	–	+	+
Plus thiazolidinediones	++	+	++	+	++	++	+	+	–
Plus DPP-4/GLP-1	++	++	++	+	–	–	–	++	+
Plus α-glucosidase inhibitors	++	+++	+++	–	–	–	–	+++	++