Exercise and Type 1 Diabetes

CGM and Exercise for Type 1 Diabetes

Exercise changes glucose in ways that differ from person to person and session to session. CGM is the tool that lets you see what is actually happening in real time.

What this page is for

This page is a starting point for understanding the relationship between physical activity and glucose in type 1 diabetes. It was originally a video summary of teaching delivered at ISPAD, BSPED, and the Diabetes Technology Network.

The video below covers the core concepts. The related reading below points to the deeper guides on exercise, activity snacking, and automated insulin delivery with exercise.

Exercise CGM

Video overview: CGM and exercise teaching

This 25-minute video summarises the core teaching on CGM use during and after exercise in type 1 diabetes. It covers the main mechanisms behind glucose responses to activity and what CGM data tends to show.

The video is for educational purposes only. Individual glucose responses to exercise vary significantly depending on insulin on board, exercise type, duration, intensity, residual beta-cell function, and timing relative to meals. Use your own CGM data to explore where you sit.

Watch: CGM and exercise in type 1 diabetes (YouTube)

Why exercise and glucose are complicated in type 1 diabetes

In people without diabetes, the body adjusts insulin and glucagon automatically during exercise. In type 1 diabetes, injected or infused insulin cannot respond dynamically to the exercise signal. This means the glucose response depends heavily on how much insulin is circulating at the start of activity.

  • Aerobic exercise in the presence of insulin tends to lower glucose, sometimes rapidly.
  • Anaerobic or high-intensity exercise can raise glucose acutely, then lower it hours later.
  • The effect on glucose extends for up to eleven hours after exercise ends, through mechanisms including increased insulin sensitivity and ongoing glycogen replenishment.
  • Residual beta-cell function (measured by C-peptide) significantly affects how glucose responds to exercise in type 1 diabetes.

These are average patterns. Your own CGM trace after different types of activity is the most useful data you have.

This content is for educational exploration only. It describes average responses and general principles. It is not medical advice and cannot replace individual clinical guidance from your diabetes care team.

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