Turning CGM Data Into Dosing Insights
CGM data can feel like a fire-hose of numbers. The magic happens when you translate those numbers into dosing insights. Below are four common post-meal curves, why they happen, and practical tweaks drawn from Jenny Smith, CDE and Scott Benner's Pro Tip and Bold Beginnings discussions.
Think of insulin as a freight train — if it leaves the station after the carbs, it can only chase, not block, the peak. The earlier insulin gets momentum, the smaller the mountain you have to climb later.
- Time the pre-bolus, not just the carbs. Watch how long it takes your rapid-acting to nudge the CGM arrow south — that delay becomes your personal pre-bolus window.
- No time? Consider a "super-bolus." Front-load part of the next two hours of basal into the meal dose and temporarily dial basal back.
Bolusing long before the first bite can let insulin win the tug-of-war before glucose even arrives. Jenny reminds listeners that "rapid isn't rapid" — fear-based extra-early dosing often backfires.
- Shorten the lead-time when the meal is low-GI, heavily protein/fat, or when starting BG is already drifting down.
- Split the meal — eat ~70% up-front, then finish the plate an hour later to catch the early dip.
- Use extended/dual-wave boluses so only a portion lands up-front and the rest trickles in as food digests.
A CGM line that "climbs the Price Is Right mountain" in a gentle, steady grade usually means the amount was close but not quite enough. The longer the slope continues, the harder it becomes to pull back.
- Add a modest correction early — before the slope becomes a plateau.
- Re-check carb-ratio accuracy. If a certain food always needs +10–15%, that's a sign to talk to your team about updating the setting rather than chasing it later.
- Confirm basal first. When basal is underpowered, meal insulin covers basal's job too — yielding exactly this hover effect.
Over-coverage often shows up after the carb surge is gone. Use a "super-bolus" only if you're ready to trade back some basal afterward — otherwise the excess drags glucose down in the second or third hour.
- Basal reduction. After a heavy upfront dose, this is where care teams often reduce or suspend basal for 1–2 hours — commonly by 50–100%.
- Consider square/extended bolus for fat-heavy or dense-carb meals — let insulin drip over 90–180 min.
- Keep rescue carbs handy. Quick glucose plus protein/fat can smooth the landing.
Strategy Visualizer — Pharmacokinetic Simulator
Adjust meal macros, timing, and insulin settings to see how each variable shapes the predicted glucose curve. All insights update in real time as you drag the sliders.
Bolus Strategy Visualizer
Drag sliders to explore how pre-bolus timing, dose size, meal composition, and extended delivery interact.