Objective: Streptozotocin-induced type 1 diabetes in experimental animals inhibits cholesterol synthesis and increases cholesterol absorption. In contrast to human type 2 diabetes, virtually no information is available on cholesterol synthesis and absorption in type 1 diabetes.
Research design and methods: We studied the variables of cholesterol metabolism in 27 patients with type 1 diabetes and in 10 patients with type 2 diabetes matched for body weight, using cholesterol precursor sterol ratios to cholesterol as surrogate markers of synthesis, and those of cholestanol and plant sterols of cholesterol absorption. Glucose control was good in all subjects.
Results: Total and HDL cholesterol and LDL triglycerides were higher in type 2 than in type 1 diabetes. Serum sterols, measured also in VLDL, intermediate-density lipoprotein (IDL), LDL, and HDL, were transported up to >90% by LDL and HDL in type 1 diabetes. The ratios of all absorption sterols in serum and in each lipoprotein were higher, and those of the synthesis markers, especially cholestenol and lathosterol, were lower in type 1 than in type 2 diabetes.
Conclusions: In contrast to type 2 diabetes, the findings in type 1 diabetes could be related to low expression of ABC G/5 G/8 genes, resulting in high absorption of cholesterol and sterols in general and low synthesis of cholesterol.