Abstract

The San Diego Zoo currently manages several diabetic primates. This abstract will focus on those managed using insulin injections. The diagnosis of diabetes has been based on urinary glucose and ketone concentrations, blood glucose concentrations, and insulin levels. There are three animals being treated with insulin (Table 1). Three types of insulin are used to manage these animals: a combination product containing 70% isophane insulin and 30% regular insulin (Humulin 70/30, Eli Lilly and Company, Indianapolis, IN, USA); regular insulin (Humulin R, Eli Lilly and Company, Indianapolis, IN, USA); and ultralente insulin (Humulin U, Eli Lilly and Company, Indianapolis, IN, USA). Historically, blood glucose measurements were obtained infrequently. The male drill was trained for venipuncture but was frequently uncooperative. The female drill was trained for toe sticks, however, discomfort prevented getting them on a frequent basis. Monitoring was based on urine glucose and ketone readings three times daily and intermittent blood glucose measurements. Glucometers (FreeStyle glucometer, TheraSense, Inc., Alameda, CA, USA) that allow blood glucose measurements on a very small amount of blood have recently become available. Therefore, more areas of the body can potentially be used for blood stick sites versus just the toes or fingers. All three animals have been trained for regular blood sticks. Keepers have been trained to perform blood glucose measurements and to administer insulin injections. They check the blood glucose concentrations three times per day for the drills and 2–3 times per week for the mangabey. A sliding scale has been developed for dosing the insulin at each treatment in the drills. The dose of insulin is based on what the blood glucose concentration is at that time. The golden-bellied mangabey has a set dose for A.M. and P.M. treatments since daily blood glucose measurements are not done. The treatment intervals are not ideal due to keeper schedules. The A.M. and P.M. doses of insulin are approximately 7–8 hours leaving approximately 17 hours between the P.M. insulin and the next A.M. insulin. A long-acting insulin (ultralente) is used in the P.M. to extend the action of the insulin during this prolonged period. Regular insulin is also administered along with the ultralente insulin in the P.M. to affect an initial reduction in blood glucose levels as well as reduce postprandial blood glucose elevations. The combination isophane/regular insulin product is given in the A.M. Additional regular insulin may be added to the A.M. treatment if the blood glucose is high. Fructosamine and glycosylated hemoglobin are measured opportunistically. These results are used in addition to the blood glucose levels to evaluate how well an animal is being regulated. Variability in response to insulin between individuals as well as within an individual over time has been observed. There are periods when an animal’s response to insulin increases or decreases. Frequently, the exact cause of this change cannot be identified. Through better regulation of diabetic primates, the long-term survival can be enhanced while reducing the amount of secondary diseases associated with diabetes mellitus.

Table 1. Primates currently managed with insulin at the San Diego Zoo