Endocrinologist must handle pre-PET insulin pump instruction

March 13, 2018 - 9:05am

       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.
       I must emphasize that insulin pumps are prescribed and administered only by experts, and that almost always means endocrinologists, who specialize in diabetes. Thus, only her endocrinologist should be the one giving orders on the insulin pump and on subcutaneous injections (if her diabetologist agrees with me).
       A PET (positron emission tomography) scan is used to find areas of high metabolic activity, usually in people with suspected cancer. A radioactive analogue of sugar, usually fluorodeoxyglucose, is injected and will be taken up by cells that use a lot of sugar, which includes most cancer cells. A person needs to be very still after the injection, or the muscles will take up the FDG, which may confuse the results. However, the cells are less likely to take up FDG in people with high blood sugar, which is why the blood sugar needs to be well-controlled (usually below 150, as you were told).
       I hope the results for your wife are favorable.
       DEAR DR. ROACH: Recently I read in your column about a woman who wrote about her "total" hysterectomy. I was hoping that in your reply you would clarify the meaning of the word. There is a common misunderstanding that if someone has a "total" hysterectomy, that includes the ovaries and/or tubes being removed as well. The word "hysterectomy" refers only to the uterus being removed.  If someone has tubes removed, it is a salpingectomy; if she has ovaries removed, it is an oopherectomy. A total hysterectomy therefore really would mean the entire uterus (and only the uterus) being removed. Occasionally women do undergo a "partial" hysterectomy, but that is more accurately called a supracervical hysterectomy (meaning, only the cervix part of the uterus remains). While this is certainly a mouthful of words, it is important for women to know exactly what was removed for the best subsequent gynecologic care. -- Dr. Allison Duncan
       ANSWER: I thank Dr. Duncan for writing, and agree with her that a patient should know exactly what operation was done. It has serious implications on subsequent risk of diseases, including breast cancer and osteoporosis, as well as the obvious effect on cervical and ovarian cancers.
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       Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to [email protected] or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.
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