Hybrid closed loop pumps

Exercise and Hybrid Closed Loop Systems

August 25, 2021

When people hear the word “diabetes” they often think of diet and exercise, given its importance with the management of type 2 diabetes and that type 2 diabetes is much more common than type 1 diabetes. For type 1 diabetes, exercise is also incredibly important, but it can be difficult for people with type 1 to manage their blood sugars while exercising.

In 2019, the Journal of Diabetes Science and Technology published a study about the use of social media to help understand barriers to exercise for adults with type 1 diabetes.1 They found three common themes:

  1. Major planning is required for exercising with T1D
  2. Lows often interrupt exercise
  3. Normal activity can cause lows and more sensitivity to insulin, despite not being considered exercise

More recently, in July 2021, the Diabetes Technology Research Group (DTRG) in Melbourne, Australia published the first Randomized Controlled Trial of the Hybrid Closed Loop (HCL) Medtronic 670G system compared to injections or insulin pumps.2 The researchers conducted a sub-study as part of the trial that looked at adults exercising for 45 minutes of moderate-intensity and high-intensity exercises to see how the HCL system would perform.

Of the 10 participants who participated in this sub-study, six were randomized to the HCL system and four to standard care. In addition to the CGM data, blood was drawn to measure venous glucose, ketones, lactate, and counterregulatory hormones at 15 minute time frames from before to almost two hours after the exercise. There were no differences between the HCL system and standard therapy on ketones, lactate or the counterregulatory hormones.

The HCL system did increase the time in range by 23%, without increasing low blood sugars for the participants. One of the co-authors, Dessi Zaharieva, PhD, stated, “This study by Dr. Paldus and colleagues demonstrated significantly improved glucose time-in-range with hybrid closed-loop during, and up to 24 hours after moderate-intensity and high-intensity exercise compared to standard therapy.”

Hopefully, the continued increase in use of hybrid-closed loop systems will help reduce the barriers to exercise for people with type 1 diabetes. For more information, see Diabetes and Exercise by Kim Rose, RDN, CDE, CNSC, LD.


  1. Using Social Media to Broaden Understanding of the Barriers and Facilitators to Exercise in Adults with Type 1 Diabetes
  2. First Randomized Controlled Trial of Hybrid Closed Loop Versus Multiple Daily Injections or Insulin Pump using Self-Monitoring of Blood Glucose in Free Living Adults with Type 1 Diabetes Undertaking Exercise

Written and clinically reviewed by Marissa Town, RN, BSN, CDCES