Control: control group (n = 6), DM+NS: diabetic group (n = 6), pre-treatment: preventive group (n = 6), DM+LC (L): low-dose therapeutic group (125mg/kg, i.g.) (n = 6), DM+LC (H): high-dose therapeutic group (250mg/kg, i.g.) (n = 6). All administrations of LC were given orally. HFD: high-fat diet; STZ: streptozotocin; LC: L-carnitine; CB: citrate buffer. At the age of 6 and 9 weeks, mice were injected twice with STZ or CB, respectively.