Table 1.

Study design. CRL—control group, IGT—impaired glucose tolerance group, IGT MET—impaired glucose tolerance + metformin group.

Groups	4 Weeks	Induction of IGT on 29th Day	4 Weeks	8 Weeks	Necropsy after 16 Weeks
CRL	Standard diet	-	Standard diet	Standard diet	Assessment of the composition of the intestinal microbiota. Isolated heart perfusion
IGT	High-fat diet	Injection of nicotinamide and streptozotocin	High-fat diet	High-fat diet
IGT MET	High-fat diet	Injection of nicotinamide and streptozotocin	High-fat diet	High-fat diet + metformin treatment

Body weight and food consumption measurement every 2nd day. BGL assessment on 28th, 56th, 63rd, 70th, 76th, 84th, 91st, 98th, 105th, and 112th days of the experiment at the same daytime (not fasting measurement). The blood samples were taken on the 112th day for additional biochemical study.