FAQ: Activity, Exercise, and Type 1 Diabetes

This FAQ is for informational purposes only. It does not replace medical advice. Always consult your healthcare professional before making therapy changes.

Prepared by John Pemberton & Prof. Othmar Moser, with years of help (in alphabetical order) from:
Dr. Peter Adolfsson, Francesca Anna RD, Prof. Rob Andrews, Dr. Cat Russon, Dr. Carmel Smart, Prof. Mike Riddell, Dr. Dessi Zaharieva — plus many others!

🎧 First, listen to the full conversation:
👉 Episode 18 — Exercise without fear: the Before–During–After playbook with Prof. Othmar Moser

Introduction

Living with type 1 diabetes means learning how different kinds of movement affect your glucose. Not all movement is the same. In this FAQ we separate activity from exercise, explain why both matter, and walk through practical steps for safe and effective glucose management.

This page draws on research, consensus guidelines, and lived experience — combining evidence with practice.

Part 1: Activity vs. Exercise

Q: What’s the difference between activity and exercise?

  • Activity = everyday movement — walking, cycling to the shop, gardening, playing with your kids.
  • Exercise = structured, deliberate training — running, lifting weights, team sports, endurance sessions.

👉 Think of activity as a glucose & health tool, and exercise as fitness and performance training.

See Activity overview

Q: Why does the distinction matter?

  • Activity: very low risk of hypoglycemia, immediate glucose benefits, achievable for everyone.
  • Exercise: higher risk of hypoglycemia, requires planning (Before–During–After), but brings fitness and performance benefits.

Part 2: Activity FAQs

Q: Why focus on 10 minutes of activity after meals?

A short 10-minute walk after eating:

  • Lowers the post-meal glucose peak.
  • Speeds up insulin action.
  • Builds confidence that physical activity is safe.

See Exercise overview

Q: What if my glucose is high — above 10 mmol/L (180 mg/dL)?

If you’ve eaten in the last 4 hours and have insulin on board:

  • 20 minutes of light activity can lower glucose by ~2 mmol/L (~40 mg/dL).
  • Avoid if ketones are elevated.
  • This can be safer and faster than stacking correction doses.

See Activity Snacking and download 20 by 2 and 20 by 40

Or as Grace would say, Daddy, you got ’99 Problems, But High Ain’t One!’ (download and share widely)

Q: How does CGM help with activity?

Continuous glucose monitoring (CGM) provides real-time biofeedback:

  • Shows flatter post-meal peaks after a 10-minute walk.
  • Makes the benefits of activity visible, especially for children.
  • Builds motivation — people see activity working immediately.

See CGM Series

Summary Physical Activity and T1D FAQ

Part 3: Exercise FAQs

Q: What’s the main risk with structured exercise?

Hypoglycemia.
Unlike activity, structured exercise often comes with a significant drop in glucose.
That’s why planning is needed.

Q: How do I plan exercise safely?

We use a Before – During – After framework.

Before exercise

  • Know your usual glucose response to that activity.
  • If on an AID system: set exercise mode/temp target 1–2 h before.
  • If on pump therapy: reduce basal 50–80% 1–2 h before.
  • Eating and insulin rules:
    • Aim to have the last meal and bolus insulin more than 3 hours before
    • If eating within 2 hours, aim to eat within 1 hour with 25-50% bolus insulin reduction.

During exercise

  • Target starting glucose: 7–10 mmol/L (126–180 mg/dL).
  • Check glucose every 20–30 min.
  • Supplement carbs early and in small amounts (3–20 g).
  • CGM is excellent, but:
    • Arrows down + <7 mmol/L? Consider a fingerstick — CGM can lag.
  • Aim to stay 7–10 mmol/L (126–180 mg/dL).

See Exercise carbohydrate calculators

After exercise

  • Biggest hypo risk = first hour after exercise.
  • Evening sessions: second risk window at ~2 a.m.
  • AID systems: keep exercise mode/temp target on for 1–2 h after.
  • Pump therapy: continue basal reduction for ~2 h.
  • MDI: if eating, reduce bolus 25–50%.
  • 20 g protein before bed can help stabilise overnight.

Summary Exercise and T1D FAQ

Part 4: Benefits of Activity Overall

Q: Why prioritise activity if I already exercise?

Because activity brings unique benefits beyond formal training:

  • Glucose control: smooths post-meal peaks, reduces corrections.
  • Insulin sensitivity: lowers total daily insulin needs.
  • Cardiovascular protection: activity is more protective than small HbA1c differences.
  • Mental health: lowers stress and depression risk.
  • Longevity: people with type 1 who stay active are often healthiest into their 70s and 80s.

Final word

Glucose management in type 1 isn’t just about numbers — it’s about movement.

  • Activity: low risk, high reward, everyone can do it.
  • Exercise: higher risk, but powerful when planned with Before–During–After.

Both matter. Both improve health.

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Disclaimer

This FAQ is for informational purposes only. It does not replace medical advice. Always consult your healthcare professional before making therapy changes.

Prepared by John Pemberton, supported by AI assistant (“Chad”). Ideas, insights, and responsibility remain with John.