Dear Dr. Roach: My wife is a Type 1 diabetic. She uses an insulin pump to control her sugar. She needs to have a PET scan. The prep for this test is fasting for six hours prior, along with no insulin for six hours. She was told to turn off her pump. Her blood glucose must be 150 or lower for the test. Even when she has fasted for 12 hours and her blood glucose is at 116, with her pump off, two hours later her BG is over 200. How do we get this test done? — S.L.H.
Answer: An insulin pump is a programmable device that continuously injects a variable amount of insulin just below the skin, where it quickly enters the bloodstream. It most often is used by Type 1 diabetics, where it is often the most effective way of managing blood sugars, especially in people who have had trouble controlling their sugars with other means.
The insulin used in an insulin pump normally is very short-acting, so a few minutes after the pump is shut off, the blood sugar will start to rise. Since that is extremely dangerous in people with Type 1 diabetes, I would suggest a dose of longer-acting subcutaneous insulin before the pump is turned off.