Episode 18 — Exercise without Fear: the Before–During–After Playbook

About the Guest

Prof. Othmar Moser is an exercise physiologist and guideline author in diabetes technology (CGM and AID). Living with type 1 diabetes, he brings lab-grade evidence into real-world routines — from weekend walks to elite sport.

Guest: Professor Othmar Moser, exercise physiologist, guideline author (CGM and AID), lives with type 1 diabetes.
Host: John Pemberton, The Glucose Never Lies.
Length: approximately 60 minutes

An exercise and activity FAQ was built on the back of this episode and is kept continuously updated.

What This Episode Explores

• Why general movement is low hypo-risk and hugely beneficial — the case for 10-minute post-meal walks.
• The Before–During–After framework for MDI, pump, and AID systems including CamAPS.
• How exercise mode and temporary targets work in practice, and where prandial reductions fit in.
• When CGM is reliable during exercise — and when a fingerstick matters (for example: double-down arrows with insulin on board).
• Night-time strategies after evening activity: temporary targets, basal adjustments, and a 20 g protein snack.
• Performance nuance: when some people prefer manual mode for consistency in competitive sport.

Key Quotes from the Episode

Quick Takeaways

• Post-meal movement: 10 minutes after each meal tends to flatten the post-meal peak and builds confidence over time.
• Insulin on board matters: starting exercise with high IOB is a key driver of hypos on average. Starting exercise mode around 2 hours before helps; 1 hour still makes a difference.
• Prandial reductions: if eating less than 2 hours before exercise, a starting point of around 25% bolus reduction is often explored — then fine-tuned with CGM data. Keeping the meal within 1 hour before exercise tends to reduce glucose spikes.

• During exercise: many people aim for 7–10 mmol/L (126–180 mg/dL); carbohydrate top-ups of 3–20 g depend on trend, therapy, and individual response. Checking every 20–30 minutes is a common starting point.
• Double-down arrows below 7 mmol/L: this is worth considering a fingerstick — exercise increases CGM lag risk.
• After exercise: the highest hypo risk tends to fall in the first hour post-exercise. Evening sessions can cause drops around 2 a.m. on average.
• Overnight: 20 g protein before bed is one strategy explored for a gentle overnight glucose rise; modest carbs may suit those not using AID.
• Big picture: 70% TIR combined with daily activity often supports long-term health better than 100% TIR with no physical activity — based on what the evidence tends to show.

Chapter Guide

• 00:00 Intro and why the show exists
• 01:30 Meet Prof. Othmar Moser
• 06:00 How consensus guidelines are made — and why they’re practical, not perfect
• 11:00 The exercise discs: planned vs unplanned; insulin and carb logic
• 17:00 Before exercise: temp targets, prandial reductions, timing your meals
• 25:00 During exercise: ranges, carb top-ups, CGM vs fingerstick
• 35:00 After exercise: the first hour, evening drops, protein strategy
• 45:00 AID nuance: manual mode for consistency; hybrid solutions for athletes
• 52:00 Future: faster insulins, fully closed loop, glucagon co-hormone systems
• 57:00 Q&A highlights, wrap-up and key messages

Resources Mentioned

• AID and exercise position papers (2025)
• CGM and exercise position papers (2020)
• GNL Exercise and CGM Guide
• GNL AID and Exercise Guide
• GNL CGM Guide
• GNL AID Guide

AID exercise discs from the consensus guidelines, adapted for clinic use:

• CamAPS Clinic Guide (PDF)
• Omnipod 5 Clinic Guide (PDF)
• T-Slim Clinic Guide (PDF)
• MiniMed 780G Clinic Guide (PDF)