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Survive & Thrive · Exercise Series

Exercise on Pump Therapy — non-AID insulin pump: the temp basal advantage

Side 1 of 2
The majors & pre-exercise
Pump therapy · non-AID
Exercise framework

The three variables that decide almost everything

IOB
Insulin on Board is variable #1 On a pump, you can lower both bolus IOB (by reducing meal dose) and basal IOB (by setting a temp basal). MDI users can only do the first.
Bolus reduction
25-75%
pre-exercise meal · Rabasa-Lhoret
Temp basal
-50%
typical starting reduction
Lead time
60-90 min
pre-exercise basal drop
Ref: Rabasa-Lhoret 2001 · West 2011 · Moser/Zaharieva 2024 EASD/ISPAD · Campbell 2015.
The three majors
✓1 · Insulin on Board. Bolus IOB + basal IOB. Pumps let you adjust both - but basal changes take 60-90 min to show effect.
✓2 · Starting glucose. Same as MDI - where you start shapes where you land.
✓3 · Trend arrows. Direction + speed still matter. Flat-line exercise is rare.
✓Temp basal is your pump-specific lever. 50% reduction 60-90 min pre-exercise is the standard starting point.
✓Disconnection is an option for short high-intensity sessions - know your pump's basal deficit recovery.
Pre-exercise · the temp basal timing

When to start reducing basal

Session typeTemp basalStartDuration
Moderate aerobic 30-60 min-50%60-90 min preUntil 60 min post
Long aerobic > 60 min-50 to -80%90 min preUntil 2 h post
Short high-intensityConsider disconnectionBefore sessionMax 60 min off
Evening exercise-30 to -50%During + until bedProtects overnight
Temp basal on its own is rarely enough. Combine with pre-meal bolus reduction (if exercise is within 90 min of a meal) and mid-session carbs.
Pump disconnection

When to disconnect, when not to

  • Disconnect for < 60 min - acceptable basal deficit. Resume at set rate afterwards.
  • Disconnect for contact sports - pump safety trumps basal continuity for short sessions.
  • Swimming - most pumps not fully waterproof. Disconnect or use a waterproof case.
  • Do not disconnect > 60 min without a top-up correction - basal deficit becomes clinically significant.
  • Omnipod is waterproof - no disconnection needed for swimming.
Pre-exercise · starting glucose

Treat pump and MDI the same way here

Glucose at startAction (moderate aerobic, 30-60 min)
< 5.0 mmol/L15-30 g carb, re-test. Temp basal -50% already in effect.
5.0-7.010-20 g carb, start with caution.
7.0-10.0Start as planned. Likely ideal.
10.0-15.0Start. Consider a small correction if trending up. Check ketones if high for hours.
> 15.0Delay if ketones present. Check set - pump failure is the #1 cause of unexplained highs.
Trend arrows + temp basal interaction

Reading the arrow through the algorithm-free lens

  • Rising arrow pre-exercise - your temp basal will amplify once the excursion peaks. Usually no extra action.
  • Flat arrow - baseline. Follow the timing table.
  • Falling arrow - temp basal + carbs. 15-20 g even if glucose is in range.
  • Two arrows down - treat as pre-hypo. Delay, retest, restart temp basal later.
Survive & Thrive · Exercise Series

Exercise on Pump Therapy — during, after, and overnight

Side 2 of 2
Carbs, recovery & overnight
Pump therapy · non-AID
During exercise · carbs in

Combine temp basal with fuel

Temp basal reduces insulin supply. Carbs replace glucose burned. The two together stop hypos.

  • Light 30-60 min: 10-15 g every 30 min if glucose falling.
  • Moderate 30-60 min: 15-30 g every 30 min.
  • Heavy / prolonged > 60 min: up to 1 g/kg/hour (Riddle 2000).
  • Intermittent high-intensity - glucose often rises from sprints. Less carbs during, more attention post-session.
Non-carbohydrate counter-regulation

The 10-second sprint trick

A brief maximal sprint at the end of moderate exercise attenuates the post-exercise glucose drop without extra carbs (Bussau 2006). Useful if temp basal is already protecting you and you'd rather not stack more food on top.

Iscoe & Riddell extend the principle: intermittent high-intensity intervals within continuous moderate exercise reduce the overall glucose fall. Pump advantage - temp basal covers the intermittent-intensity risk.
Post-exercise & overnight

Sustained temp basal reduction - the pump advantage

On MDI, you can't reduce basal. On a pump, you can - and this is where the biggest overnight hypo protection comes from.

  • Keep temp basal -30 to -50% for 2-6 hours post-exercise after significant sessions.
  • Evening exercise: consider -30% temp basal until morning.
  • Bedtime snack 0.4 g/kg slow carbs (Campbell 2015) even with temp basal - they work together.
  • Mixed-macronutrient snack (milk + oat biscuit) outperforms quick carbs for overnight stability (Kalergis 2003).
  • Set a 3am alarm for the first few sessions of any new activity until you know your pattern.
Major in the majors · the two actions

Model before you act

Action 1 Exercise IOB - carbs for 30 min exerciseBolus IOB + basal IOB. Pump-specific calculation. Plans your carb load. → Action 2 Exercise Planning ExplorerTemp basal + bolus reduction + carbs, modelled for your pump and session. →
Go deeper

GNL explorers, guides & podcasts

GuideFull Exercise Guide - 5-part seriesAerobic, mixed, anaerobic and AID + exercise.→ ExplorerActivity Explorer - 10, 20, 30 min walkingWhen exercise is the treatment for a high.→ AskGrace - evidence-backed Q&ARabasa-Lhoret, Bussau 10s sprint, Moser/Zaharieva 2024.→