Exercise adds to metformin and acarbose efficacy in db/db mice

Physical exercise is frequently recommended for the treatment of type 2 dia betes, whether as primary therapy with diet modification or as an adjunct t o drug therapy. We hypothesized that mild exercise would enhance the glucos e-lowering effects of 2 oral antihyperglycemic drugs, metformin and acarbos e, in an animal model of type 2 diabetes, Eight-week-old male C57BL/Ks (db/ db) mice were sorted into control and exercise groups and dosed daily for 4 weeks with vehicle, metformin (150 mg/kg/d), or acarbose (40 mg/kg/d). Exe rcise consisted of swimming (initially 5 min/d and ultimately 1 h/d for the last 2 weeks). Exercise, metformin, and acarbose independently reduced ser um glucose concentrations 15% to 25% compared with the respective controls (P < .0001), but the effect on glucose concentration of combining drug ther apy with exercise was no greater than the sum of the individual effects. Ex ercise training independently increased muscle glycogen (30%; P < .05) and liver glycogen (250%; P < .05) levels and slightly reduced serum high-densi ty lipoprotein cholesterol (-8%; P < .05), whereas drug treatment had no ef fect on these variables. In addition, exercise but not drug treatment preve nted the approximately 30% decline in serum insulin concentrations that occ urred in the control animals (P < .05). Twenty-four hours after the last dr ug or exercise treatment, oral glucose tolerance and hemoglobin Ale were no t significantly different between groups. Treatment also did not greatly af fect triglyceride, glycerol, or total cholesterol concentrations. In conclu sion, exercise and drug therapy independently decreased serum glucose in db /db mice, and these effects did not appear to be synergistic. In addition, exercise training maintained serum insulin concentrations and increased tis sue glycogen storage. These results suggest that exercise has the potential to add to the efficacy of oral antihyperglycemic drugs. Copyright (C) 2001 by W.B. Saunders Company.