Optimizing Insulin Absorption and Insulin Injection Technique in Older Adults

Overview

To determine which anatomic site offers the most consistent (superior) absorption of insulin. To determine the injection technique which allows the most consistent subcutaneous injection of insulin (to pinch or to spread). Hypothesis: Based on age-related changes in the amount of subcutaneous fat we anticipate that the absorption of insulin from various anatomical sites will differ. Justification: To date health care professionals have extrapolated data obtained from younger adults and applied the results to the elderly. Objectives: To determine the rate of insulin absorption from different anatomic sites in diabetic patients over the age of 70. To determine the best practice for subcutaneous injection in older adults. Research Method: Measurement of serial glucose and insulin levels using 360 minute euglycemic clamp studies. Statistical Analysis: Paired t test, repeated measures ANOVA

The study will consist of 5 visits to the UBC VITALiTY Research Centre. At the screening visit subjects will have the following information collected: height, weight, blood pressure, heart rate, BMI, medical history and concommitant medications. Approximately 15cc of blood will be drawn and analyzed for A1C, CBC with platelets, AST, ALT, alk phos, BUN, creatinine, fasting blood sugar. The subjects will undergo 4 euglycemic clamp studies at least 30 days apart in random order. During one study subjects will receive the insulin injection in the abdomen using the pinch technique. In another study the subjects will receive the insulin injection using the spread technique. During a third study the subjects will receive the insulin injection in the deltiod area using the pinch technique. During a fourth study the subjects will receive the insulin injection in the deltoid using the spread technique. Subjects will be randomly assigned to the studies. After each injection the subject will complete a questionnaire to rate comfort of the injection. Subjects will report to the Research Centre at 0700 having fasted since midnight the night before. An intravenous line with normal saline will be placed in one hand to facilitate blood drawing. This hand will be placed in a heated box. A second intravenous will be inserted in the arm for the infusion of glucose. Prior to subcutaneous insulin injection, blood samples will be collected at -30, -15, and 0 minutes. At time 0 the subcutaneous injection of lispro insulin (0.1 u/kg)will be administered and the glucose infusion will be started. Glucose levels will be measured at the bedside every 5 min and insulin levels every 15 min from 0-360 min. Glucose infusion will be adjusted to maintain glucose levels at a constant level for the duration of the study, using the glucose clamp protocol.