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Diet and Exercise with Automated Insulin Delivery

A team of world-renowned experts in diabetes presented updates about automated insulin delivery (AID), focusing on the role of diet and exercise for closed-loop systems. 

Dr. Boris Kotavchev of the University of Virginia began by comparing the different types of AID systems available on the market now. 

Kotavchev said that as we develop more advanced systems, manufacturers should emphasize ease of use. However, he noted that such direct comparisons between systems may not be entirely accurate since different CGMs can result in different outcomes. 

Dr. David Maahs of Stanford University outlined the steps that physicians should take to adjust AID systems for their patients. He emphasized the racial and socioeconomic disparities in access to diabetes technology. 

Dr. Laurel Messer of the University of Colorado School of Medicine discussed strategies to prevent highs and lows surrounding exercise while using AID. “Exercising is important because it improves cardiovascular (heart) disease risk profile and leads to decreased retinopathy and microalbuminuria in adults,” she said. 

The main challenges with unstable glucose levels occur in two stages: pre-exercise and post-exercise. Messer said, “Pre-exercise insulin-on-board can lead to hypoglycemia during exercise while post-exercise glycogen (glucose stored in the liver) replenishment can lead to hypoglycemia risk for 24+ hours.” 

She noted that the goal was to reduce basal and bolus insulin. Since aerobic exercise may lower glucose and anaerobic exercise may increase glucose, she recommends a “mixed exercise” that involves “aerobic exercise with higher intensity.” 

While exercise management is mostly trial and error, Messer emphasized it was crucial to reduce insulin-on-board at the time of exercise to prevent hypoglycemia.

Dr. Stuart Weinzimmer of Yale University School of Medicine built on the exercise discussion by turning his focus to diet and AID. He said that in addition to high carb meals, high protein and high-fat meals also contribute to hyperglycemia. 

As users consider switching to closed-loop systems, Weinzimmer’s overarching message was that you should know your closed-loop system well, consider prior meals and activity, and that the superiority of extended bolus vs. simple corrections is still not established. 

In other words, even with a closed-loop system, food choices still matter.