OBJECTIVETo study effects of insulin treatment on intracellular lipid content in livers and insulin resistance of type 2 diabetic rats.

METHODSType 2 diabetic rats were induced by injecting streptozotocin (25 mg/kg) and fat rich food. Then according to the results of the oral glucose tolerance test (OGTT) and glucose-induced insulin secretion test (IST), the rats were divided into two groups: control group (DC) and insulin treated group (DI). Normal rats (NC) served as controls. The treatment of each group with either NPH insulin (4 approximately 6 U . kg-1. d-1), or saline continued for 4 weeks. Body weight, OGTT, IST, blood lipids, intracellular lipids in liver and liver histology were studied. The insulin sensitivity index (ISI) was applied to assess the status of insulin resistance.

RESULTSBlood lipid and intracellular lipids in livers in the DC were higher than those in NC (t = 2.59 approximately 15.77, P < 0.05) and the ISI was lower (t = 3.16, P < 0.05), with many fatty droplets appearing in the livers. In comparison to DC, DI showed that blood lipids were decreased, but lipids in livers were markedly increased (TG, TC, FFA increased 55.7%, 19.87%, 22.2%, respectively), and fatty droplets in hepatocytes were larger, but the ISI did not change significantly.

CONCLUSIONInsulin treatment can make blood glucose normal, increase the intracellular lipid content in the liver, and not increase the insulin resistance significantly.