Pumps are an Adjunct, Not a Cure

An endocrinologist shares the limits and pitfalls of pump therapy, and how it can’t beat a cure.



My first patient of the day was a woman with Type 1 who had worn an insulin pump for 15 years. She was now 14 weeks pregnant. One day, she had multiple “No Delivery of Insulin” messages on her pump. She called the pump company and was told to change the tubing and set. Five changes later, the error message still wouldn’t go away. A new pump arrived the next day.

Pump failure happens, but it can be an especially dicey proposition during pregnancy, as insulin production often becomes an unknown variable for pregnant women with T1. Dr. Lois Jovanovic, a pioneer in studying T1 and pregnancy, was one of the first to find a significant rise in C-peptide production (a measure of the body’s own insulin production) in pregnant T1 women. This can cause havoc on insulin therapy. Researchers have found that up to 71% of pregnant T1 women experience severe to moderate hypoglycemia, most often between 10 to 16 weeks of gestation because of this. Dr. Jovanovic and others, including myself, have seen women with T1 come completely off insulin therapy, only to return to it within a month after delivery.

Dr. Jovanovic’s work has led many researchers to question how a woman who has made no insulin for 20 years could suddenly come off of insulin. We know that during pregnancy, the body increases production of steroids and other immunosuppressive agents so the mother’s body will not reject a fetus that only has half of her DNA. During pregnancy, many growth genes also kick into gear, including the Reg gene responsible for pancreatic repair. We hypothesize that this is why there’s a bloom in new insulin-producing cells in the diabetic mom-to-be. Such a spontaneous regeneration of insulin production inspires researchers like me that a T1 cure is possible.

With a very pregnant and very worried patient in front of me, I became acutely aware of the limits of pump therapy. Pump technology has made huge strides in recent years, but nothing is foolproof. Decades ago, my practice’s CDE, Karen Dawn, would spend weeks prepping patients for the pump. She had a long and detailed checklist of what was required before a patient was greenlighted for a pump, and even then I would still hold my breath once pump therapy started. I made myself available for a patient 24/7 after the pump was started.

Not all pump users are proactive, and some probably shouldn’t be on pump therapy at all. I still see new patients who have pumps and only use a basal setting, or who really have no idea how to use their pumps. It’s like giving someone a race-car to drive when they only know how to ride a bicycle. Some are ready to learn to drive their pumps to optimize their diabetes care; others are better off on insulin injections.

In the last decade, as pumps have become more sophisticated, so have potential pump problems. In 2002, I first received notification of an FDA recall of an insulin pump because “some pumps started programming a bolus of insulin that was not initiated by the pump user.” Before, it was almost always user error to fear. Now, we’ve had to become vigilant of computer failure, as well. At first, it was hard to fathom, like something out of a sci-fi movie. Mechanical failure is another reason pump users must be active participants in their therapy. Even then, not all errors can be avoided.

My current CDE and pump trainer, Susan Pierce, is one of the smartest people I know, especially about her own Type 1 diabetes, and even she suffered a severe episode of hypoglycemia because of a mechanical malfunction with a new insulin pump. The new pump had given her a 10-unit bolus while she was sleeping, which was a life-threatening amount for her. Fortunately, Susan was wearing a Dexcom G-4 sensor and her husband heard the sensor’s alarm for a low; Susan was unresponsive and couldn’t hear it. He was able to rouse her and help get her glucose back in the normal range.

Our team was shaken by what might have happened. We work with T1 patients every day, but this was different; Susan was one of us. She is one of the many reasons why our scientific team at Perle Bioscience is so focused on finding a way for people with Type 1 diabetes to achieve insulin independence. I am grateful for pumps, and sensors, but I am driven by Susan’s accident to get to a day when pumps and sensors are no longer needed.

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Claresa Levetan, M.D., is a noted endocrinologist with expertise spanning diverse areas of diabetes. She has been internationally recognized for the translation of science and technology into improved health care options for patients with diabetes. She served as an associate editor of the journals Clinical Diabetes and Diabetes Forecast.