Perspective: Type 1 Diabetes
Insulin pumps help people with Type 1 diabetes live more normal, healthier lives. Did you know that the first insulin pump, invented in 1963, was so large it had to be carried like a backpack? Today’s pumps fit in a pocket. They have also morphed into increasingly sophisticated “smart” devices capable of automating insulin dosing and delivery. They bring us a big step closer to an artificial pancreas. Meanwhile, insulin pumps are transforming lives by reducing the day-to-day burdens and distress of self-managing this demanding disease.
My now 7-year-old son Casey was approved for an insulin pump a year after his diagnosis. We chose the t:slim X2. Three months after learning and using its more basic technology (Basal-IQ), we updated the pump’s software to the more advanced technology (Control-IQ) after receiving online and in-person training.
Casey’s pump is a 3 x 2 x half-inch device that he wears in a skinny tummy pack. Like a miniature computer, it contains instructions for how much insulin to deliver into his body, and when. It can be updated remotely and has a touch screen with icons indicating what the pump is doing. A separate infusion set carries insulin from the pump’s cartridge to an infusion site, usually on the thigh, buttocks or belly. Casey’s TruSteel infusion set uses a thin, flexible 23-inch tube to transport the insulin from the pump to a tiny needle inserted just below his skin. We must replace the insulin cartridge and infusion set and switch the infusion site every two to three days.
Casey continues to wear another smart device–a Dexcom G6 continuous glucose monitor (CGM)—because his pump needs a steady stream of blood glucose (BG) readings. The pump must monitor trends in his BG to predict highs and lows. It can then prevent them by preemptively increasing, decreasing, or temporarily stopping insulin delivery.
Insulin pumps come with an algorithm for calculating insulin doses, but the user and their diabetes team customize its instructions by creating personal profiles. These tailor the BG target, insulin-to-carb ratio, insulin-sensitivity correction factor, and basal insulin rate to different days of the week and time segments during the day. This gives Casey flexibility in food intake and other life activities. He must still key in grams of carbohydrates eaten so that the pump will administer the bolus of insulin needed to cover food.
The pump keeps Casey’s BG within a healthier range by fine-tuning insulin doses, more as a working pancreas would. He no longer needs to take a nightly injection of long-acting basal insulin because the pump delivers micro-doses of rapid-acting basal insulin throughout the day and night. The pump also tracks active insulin remaining in his body from previous boluses, modifying bolus calculations when applicable. Crucial too, is the pump’s ability to divide bolus doses for slow-digesting food, such as pizza, as well as to prevent hypo- and hyperglycemia by predicting them 30 minutes ahead of time. For instance, it decreases doses of basal insulin when predicting a BG below 112.5, and it suspends insulin delivery when predicting a BG below 70. Insulin delivery resumes when BG rises or is predicted to. Conversely, the pump increases basal insulin when it predicts BG will rise above 160, and automatically delivers correction boluses when predicting BG above 180. Hypo- and hyperglycemic events are less likely to develop.
Two other Control-IQ features are particularly important for us. Casey is very physically active, which can have a big effect on his blood sugar. He attends summer camp, so we were excited that Control-IQ has a setting for physical activity. It also has a sleep setting for nighttime inactivity. Both settings narrow the usual target BG range of 112.5-160. The activity setting narrows it upward to a safer 140-160. The sleep setting narrows it downward to a safer 112.5-120 and enhances safety by turning off automated correction boluses. Now, alarms seldom sound during the night alerting us to too-high or too-low BGs.
Insulin pumps are intimidating because they are technologically sophisticated and can be dangerous when they fail or if users make mistakes. They aren’t a free pass to ignore BG levels and the work of controlling them. Nor can the pump anticipate and solve all problems. For example, Casey’s BG can swing wildly when he is ill or if we misestimate his carbohydrate intake, but you learn with experience and help from your diabetes team.
Casey adapted quickly to using a pump, especially because it communicates with the Dexcom G6 CGM he was already wearing, and because his smartphone was already wirelessly connected to his CGM. Dexcom’s Follow app allows me to receive alerts and BG readings on my smartphone from his. Tandem’s t:connect mobile app allows me to see his pump data discreetly on his phone, and its t:connect web application then allows us and his medical team to use the wealth of information logged over time to improve insulin dosing.
Casey has a routine down. To protect his pump, he stops insulin delivery, removes the pump and caps off the infusion site before going in water or doing jiu jitsu. If disconnecting for an hour or more, we temporarily reconnect the pump to dose him for missed basal insulin. The pump must be recharged every few days, during which time he enjoys watching TV. With supervision, he keys his carb counts into the pump. He also enters his BG level if for any reason the CGM isn’t transmitting to the pump.
The pump gives him more independence by doing much of the work we often interrupted him to do, especially injecting insulin and calculating doses. The pump has spared him much fatigue and discomfort–and his parents much anxiety—by reducing the number and severity of hypoglycemic and hyperglycemic episodes.
Thanks to the pump, we’ve regained a sense of normalcy, along with better health for Casey and more sleep for all of us. What a gift that is!
Lisa Seitles and her husband Sam are the owners of READ Preschool and Camp Tuscaloosa. They have four children and are active members of the community.