Glucose-responsive hepatic insulin gene therapy of spontaneously diabetic BB/Wor rats.

Hepatic insulin gene therapy (HIGT) ameliorates hyperglycemia in multiple rodent models of diabetes mellitus, with variable degrees of glucose control. We demonstrate here that adenoviral delivery of a glucose-regulated transgene into rat hepatocytes produces near-normal glycemia in spontaneously diabetic BB/Wor rats without administration of exogenous insulin. We compared growth, glycemia, counterregulatory hormones, and lipids in HIGT-treated diabetic rats to nondiabetic rats and diabetic rats treated with either insulin injections or sustained-release insulin pellets. HIGT-treated rats achieved near-normal blood glucose levels within 1 week and maintained glycemic control for up to 3 months. Rats treated with sustained release insulin implants had similar blood sugars, but more hypoglycemia and gained more weight than HIGT-treated rats. HIGT-treated rats normalized blood glucose within 2 hr after a glucose load, and tolerated a 24-hr fast without hypoglycemia. HIGT treatment suppressed ketogenesis similarly to peripheral insulin. However, glucagon levels and free fatty acids were increased in HIGT-treated rats compared to either nondiabetic controls or rats treated with exogenous insulin. In addition to extending successful application of HIGT to a rat model of autoimmune diabetes, these findings emphasize the relative contribution of hepatic insulin effect in the metabolic stabilization of diabetes mellitus.