What is a normal glucose baseline?

For people without diabetes, fasting and between-meal glucose commonly sits roughly in the 70 to 100 mg/dL range, though it varies by person, time of day, sleep, and stress. Your own typical pre-meal number, observed over days on a CGM, is the baseline that matters for judging meal responses.

How high should glucose go after a meal?

Post-meal glucose typically peaks 30 to 90 minutes after eating. Many wellness practitioners like to see peaks under about 140 mg/dL and rises under about 30 mg/dL over baseline in people without diabetes, with a return toward baseline within 2 to 3 hours. These are heuristics, not diagnostic criteria.

What is time in range on a CGM?

Time in range is the percentage of the day your glucose spends inside a target band, conventionally 70 to 180 mg/dL. It's a single number that summarizes how steady your day was. People without diabetes typically spend the vast majority of the day well inside that range.

Why does the same meal spike me but not my friend?

Individual glucose responses differ dramatically due to genetics, body composition, gut microbiome, sleep, stress, activity, and what else was eaten that day. Landmark research on personalized nutrition showed people can have opposite responses to identical foods. That's the core argument for measuring your own responses instead of relying on generic glycemic-index tables.

Blog · July 5, 2026 · 7 min read

Understanding your glucose curve: baseline, peak, and recovery

Your CGM draws a line all day. Most people stare at it for two weeks, feel vaguely informed, and stop. The trick is knowing that every meal writes a small story into that line, and the story has exactly four parts. Learn to read them and the wiggly line becomes a manual for your own body.

The four parts of every meal response

1. Baseline: where you started

Baseline is your glucose just before the first bite. For people without diabetes it commonly sits roughly between 70 and 100 mg/dL, drifting with time of day, sleep quality, and stress. Baseline matters because a peak of 145 means something completely different if you started at 90 versus 125. Judging a meal by peak alone, without baseline, is like judging a hill by its summit without knowing where the trail began.

2. Peak: how high, and when

After carbohydrates hit your bloodstream, glucose climbs and tops out, typically 30 to 90 minutes after eating. Two numbers live here: the peak itself and the rise (peak minus baseline). The rise is the honest measure of what the meal did. Wellness heuristics many practitioners use for people without diabetes: peaks ideally under about 140 mg/dL, rises ideally under about 30 mg/dL. Fast-digesting carbs eaten alone also tend to peak earlier and sharper than mixed meals.

3. Recovery: how long back to baseline

A healthy response comes back down within roughly 2 to 3 hours. Long tails (still elevated at hour three) suggest the meal outran your body's ability to clear it. Sharp drops below baseline, called reactive dips, often bring the crash-and-cravings feeling an hour or two after high-sugar meals. If you get sleepy and snacky at 3pm, your lunch curve usually shows you why.

4. Shape: spike vs rolling hill

Two meals can share a peak and still be different stories. A needle spike that rockets up in 25 minutes and crashes is more turbulent for energy and hunger than a gentle hill that rises the same amount over 75 minutes and eases down. Flatter and slower generally feels better, which is why tactics like meal order and carb pairing (we covered nine of them here) are about reshaping curves, not just lowering peaks.

Zooming out: time in range

Time in range is the day-level summary: what percentage of the day your glucose spent inside a target band, conventionally 70 to 180 mg/dL. It's the number that tells you whether your day was steady overall, even if one meal misbehaved. People without diabetes typically live well inside the band the vast majority of the time; watching your time in range respond to better meal choices is one of the most motivating feedback loops in metabolic health.

Why your curve isn't your friend's curve

Here's the finding that reshaped nutrition science: in landmark personalized-nutrition studies, people eating identical foods showed wildly different, sometimes opposite, glucose responses. One person's safe banana is another's 50-point spike. Genetics, body composition, gut microbiome, sleep debt, stress, and the previous meal all feed into it.

The practical consequence: glycemic-index tables and influencer food rules are population averages. Your body runs its own experiment every time you eat. The only question is whether anyone writes down the result.

Reading curves without doing homework

You can do all of this manually: screenshot your CGM graph, note when you ate, eyeball the baseline, find the peak, count the hours back down. People genuinely do this, in spreadsheets, for months.

Or the four parts arrive computed. spike reads your CGM through Apple Health (Stelo, Dexcom, Libre, or Lingo), and for every meal you photo-log it extracts the story automatically: baseline, peak, rise, time to peak, and time back to baseline, then sends the verdict as a notification. Your day view shows every meal pinned to the daily curve with time in range on top. The manual skill in this article is still worth having; you just don't need it every meal.

The bottom line

Every meal response has four readable parts: baseline, peak (and rise), recovery, and shape. Judge meals by rise over baseline rather than peak alone, expect recovery within 2 to 3 hours, and treat generic food rules as hypotheses until your own curve confirms them. Once you can read the story, the CGM stops being a gadget and starts being an instruction manual.

your curves, decoded automatically.

spike computes baseline, peak, and recovery for every meal you log. Free trial on the App Store.

Download on the App Store

This article is for general wellness education and is not medical advice. Ranges cited are common wellness heuristics for people without diabetes, not diagnostic criteria. spike is a wellness app, not a medical device. If you have diabetes or another condition, interpret CGM data with your care team.