The serum HDL2-C, HDL3-C, apo AI and apo AII levels were measured in the non-insulindependent diabetic subjects (NIDD) and normal subjects to study the metabolism of HDL in the diabetics. The serum HDL2-C levels in the insulin-treated group were significantly higher than those in the normal group in which the total cholesterol (TC), triglyceride (TG), obesity index and age were matched whereas there was no difference between the serum HDL2-C levels in the oral agent-treated group or group treated by diet only and those in the normal group. These suggest that insulin increases the HDL2-C levels and the increase of the HDL2-C levels is not directly related to changes in the serum TC and TG levels, obesity index and age. No significant differences in the serum apo AI and apo AII levels were found between the insulin group and normal group. From these results it is suggested that in the insulin group the cholesterol/apoprotein ratio in the HDL2 is higher than that in the normal group. The serum apo AI and apo AII levels were significantly lower in the diabetics with an ischemic heart disease (IHD) than those in the diabetics without the IHD. The results show that in the diabetics the apo AI and apo AII play an important role in preventing the development of IHD.
