In order to study hyperlipidemia in diabetes mellitus, rats were made diabetic by administration of streptozotocin and the optimal conditions for production of severe and persistent hyperlipoprotenemia determined. Two groups of rats were compared: rats fed sucrose-rich diets and rats fed laboratory chow. The optimal dose of streptozotocin was 45 mg/kg body weight for the sucrose-fed rats. With this dose, plasma glucose reached a maximum of over 600 mg./100 ml., and plasma insulin was reduced by 60 per cent. Plasma triglycerides rose in the sucrose-fed rats to over 1,000 mg/100 ml. two days after the streptozotocin was given and then decreased to over 770 mg./100 ml. 12 days after treatment and then to 585 mg./100 ml. 10 weeks after induction of diabetes. With this dose, ketonuria did not occur nor did any of the animals die, as occurred with higher doses. In the chow-fed rats, plasma triglyceride levels were elevated with the induction of diabetes to levels of approximately 300 mg./100 ml.
The concentration of all the plasma lipoproteins increased with the induction of diabetes. The concentration of very-low density lipoprotein (VLDL) protein in the sucrose-fed diabetic increased fivefold, the low-density lipoprotein (LDL) protein increased, and especially striking was the increase in high-density lipoprotein (HDL) protein concentration, which became more pronounced with the duration of the diabetes. The diabetes produced by streptozotocin administration to sucrose-fed rats, thus, provides a useful model for the study of the hyperlipoproteinemia of diabetes.