● Food Intelligence · Fruit

Plum Glycemic Index and Calculate Your Own Glucose Response

Across 2,152 logged meals containing plums from 948 Signos members, the average glucose peak was +33.9 mg/dL — modest for a fruit, consistent with a published GI of 26 and GL of 3. Fresh plums eaten alone anchored at +30 mg/dL; pairing with yogurt or cheese trimmed another 1–2 mg/dL, while a high-carb meal (≥60g) pushed peaks 32% higher.

GS
Reviewed by Grace Shryack
Signos Proprietary Data·Updated May 2, 2026·10 min read

● Powered by Signos cohort dataMedium confidence · n=2,152
The swap calculator below draws on 2,152 matched-pair logs — a broader cohort than the page's single-item primary, used to give every ingredient swap statistical power. Welch's t-test on matched pairs, not third-party glycemic-index tables. Each swap shows its sample size and confidence tier inline.
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Tap any ingredient below to swap it for a glucose-friendlier alternative. Your Signos Glucose Score, predicted curve, and nutrition update in real-time. Every swap is data-backed by real CGM response measurements.

Ingredients — Tap to Swap
Meal Context
Pre-meal sequence
Activity after meal
Time of day
47
of 100
Signos Glucose Score
High Spike Risk
75% of members fall between +29 and +41 mg/dL
Predicted Curve · 3-hr window
1401001201401601800m30m60m90m120m150m180m+35
Peak
+35
mg/dL
Time in Range
100%
3hr window
Above 140
0m
danger zone
Swaps
0
applied
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● Key Findings · Do plums spike blood sugar?

Not meaningfully for most members — across 2,152 logged plum meals the average peak was +33.9 mg/dL, with a median of +31 mg/dL. Across 2,152 logged meals containing plums from 948 Signos members, the mean glucose peak was +33.9 mg/dL — modest for a fruit and consistent with a published GI of 26 and GL of 3. Eaten alone (n=574) the average drops to +30 mg/dL with 33% of responses in the low-spike tier. The dominant amplifier is total meal carb load: meals with ≥60g of carbs ran 32% higher than the low-carb baseline (n=273, p<0.001, CI: [+7.73, +12.65] mg/dL). High meal-level sugar (≥20g, n=516) added another 22%. Pairing plums with cheese or yogurt trimmed peaks 1–2 mg/dL — directional, not transformative — and varietal differences (black plum −1.6 mg/dL vs. fresh) are within the noise floor of a small sub-cohort.

  • ▸Plum is one of the flatter-spiking fruits in the cohort: across 574 logs of plums eaten alone the average peak was +30 mg/dL — well below banana (+38.8 mg/dL) and apple (+31.5 mg/dL).
  • ▸Carb load is the biggest lever: meals with ≥60g carbs spiked 32% above the low-carb baseline across 273 matched logs (p<0.001, CI: [+7.73, +12.65] mg/dL).
  • ▸Cheese and yogurt pairings each trimmed peaks 1–2 mg/dL across 316 and 121 matched logs respectively — directional, not transformative.
  • ▸Snack-time logs averaged +29.8 mg/dL across 652 meals — the lowest meal-time slot, ~7 mg/dL below dinner (+36.5 mg/dL, n=387).
● Signos Rules

Three citable insights from this recipe's data

Rule 1
"The Carb-Load Penalty"
+32% peak
Across 273 logs where total meal carbs hit 60g or more, glucose peaks ran 32.3% higher than the 1,544-log low-carb baseline (p<0.001, CI: [+7.73, +12.65] mg/dL). It's the single largest modifier in the plum dataset. Even for a low-GI fruit, stacking a second carb source — toast, pastry, juice — at the same sitting is what reliably moves the curve. The plum itself is mostly along for the ride.
Rule 2
"The Snack-Time Edge"
−7 mg/dL vs dinner
Snack-time plum logs averaged +29.8 mg/dL across 652 meals — the lowest meal-time slot in the cohort, 6.7 mg/dL below dinner (+36.5 mg/dL, n=387) and 7 mg/dL below lunch (+36.8 mg/dL, n=570). The gap mostly reflects what's around the plum: snack logs are usually plum-only or plum-plus-yogurt, while dinner logs sit inside larger mixed meals. Eat the plum on its own for the cleanest curve.
Rule 3
"The Yogurt Discount"
−2 mg/dL peak
Pairing a plum with yogurt averaged +32.3 mg/dL across 121 matched logs — 2 mg/dL below the +33.8 mg/dL alone baseline (medium confidence). Cheese pairings (n=316) tracked similarly at −1 mg/dL. The effect is real but small: plum's low-GI baseline leaves little room for fat or protein to blunt further. The protein-pair modifier across the broader cohort showed only a 6.8% reduction (n=947, p=0.007) — consistent with a flat-fruit pattern.
● Curious about your own?

Curious how your body responds to plums specifically?

Across 2,152 logged plum meals, the average glucose peak was +33.9 mg/dL — but the IQR spans 24 mg/dL, from +20 mg/dL at the 25th percentile to +44 mg/dL at the 75th. That's a wide range for a low-GI fruit. Your response depends on what else is on the plate, what time you eat, and your own baseline glucose. A CGM makes that variability visible in real time.

Learn how Signos works
Why this meal spikes

This meal stacks 3 independent spike drivers — together they account for +34 mg/dL.

Driver 1
Natural sugars (~7g per medium plum)
+12 mg/dL
A medium plum carries roughly 7g of natural sugars (mostly fructose and glucose). This is the dominant driver of the +33.9 mg/dL cohort mean — modest by fruit standards and consistent with a published GI of 26 and GL of 3.
Driver 2
Total meal carb load (≥60g at the meal level)
+10 mg/dL
Meals with ≥60g total carbs spiked 32.3% above the low-carb baseline across 273 matched logs (p<0.001, CI: [+7.73, +12.65] mg/dL). This is the single largest amplifier in the plum dataset.
Driver 3
High-sugar meal context (≥20g at the meal level)
+6 mg/dL
Across 516 logs flagged for high meal-level sugar, peaks ran 21.7% higher than the 856-log low-sugar baseline (p<0.001, CI: [+4.68, +8.7] mg/dL). Sweet co-ingredients compound the plum's own modest fructose load.
● Which bucket are you in?

Some members spike +30.3 mg/dL. Others spike +41.7. The only way to know how you'll spike is to measure with a Signos CGM.

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● What surprised us
What surprised us about plums is how little anything else moves the response. Across 2,152 logged plum meals the average peak was +33.9 mg/dL; eaten alone it dropped to +30 mg/dL. Cheese pairings trimmed 1 mg/dL. Yogurt trimmed 2 mg/dL. Even the carb-load penalty — usually the biggest lever in any fruit — only added 32% on top, half the size of the same effect for peach or apple. Plum is the rare fruit where the food itself, not the plate around it, sets the ceiling.
— Signos Data Science Team

Why this happens, physiologically

Plums produce a mean peak of +33.9 mg/dL across 2,152 logged meals — among the flatter CGM responses for any fruit and consistent with a published GI of 26 and GL of 3. The IQR spans 24 mg/dL (p25: +20, p75: +44) and 41% of responses crossed +35 mg/dL. Eaten alone (n=574) the cohort mean drops to +30 mg/dL, with 33% of responses in the low-spike tier. The dominant lever is total meal carb load: meals with ≥60g carbs ran 32% above the low-carb baseline (n=273, p<0.001). High meal-level sugar (≥20g) added another 22% (n=516). Fat and protein pairings each cut peaks ~7% — directional but small, because plum's low carb load means little spike to blunt. All findings are observational from matched-pair Welch's t-tests, not controlled trials.

● Three mechanisms drive plum's glucose range

Carb load, sugar content, and meal timing together explain most of the variance in the plum cohort

  1. Mechanism 1
    +32%
    Carb-load escalation
    Meals with ≥60g total carbs averaged 32% above the low-carb baseline across 273 matched logs (CI: [+7.73, +12.65] mg/dL, p<0.001). The single largest amplifier in the plum dataset — far larger than any pairing or varietal effect.
  2. Mechanism 2
    +22%
    High-sugar context
    Meals with ≥20g sugar ran 21.7% above the low-sugar baseline in 516 matched logs (CI: [+4.68, +8.7] mg/dL, p<0.001). Plum's own fructose stacks with any added sugar in the meal.
  3. Mechanism 3
    −7 mg/dL
    Snack-time edge
    Snack logs averaged +29.8 mg/dL (n=652) vs. +36.5 mg/dL at dinner (n=387) — a 7 mg/dL gap that mostly reflects the smaller surrounding meal at snack time, not a circadian effect on the plum itself.
● Fit Check
Plums are one of the lowest-spike fresh fruits in the cohort — the meal context around them matters more than how they're prepared.
✓ This is for you if
  • ▸You eat plums as a standalone snack. Across 574 logs of plums eaten alone, the average peak was +30 mg/dL with 33% of responses in the low tier.
  • ▸You eat plums at snack time. Snack logs averaged +29.8 mg/dL (n=652) — the lowest meal-time slot in the cohort, ~7 mg/dL below dinner.
  • ▸You pair plums with yogurt or cheese. Yogurt pairings trimmed −2 mg/dL (n=121) and cheese pairings −1 mg/dL (n=316) below the alone baseline.
  • ▸You keep total meal carbs under 60g. Light-carb meals containing plums averaged +31.6 mg/dL across 1,544 logs vs. +41.7 mg/dL when carbs hit 70–110g (n=129).
✗ Not for you if
  • ▸You eat plums alongside a high-carb meal (≥60g). That bucket averaged +39.2 mg/dL (n=430) and the heaviest builds (110g+) hit +39.8 mg/dL across 49 logs.
  • ▸You eat plums at lunch or dinner with larger meals. Lunch logs averaged +36.8 mg/dL (n=570) and dinner +36.5 mg/dL (n=387) — both ~7 mg/dL above snack time.
  • ▸You eat plums in a high-sugar context (≥20g sugar at the meal level). That sub-cohort averaged 22% higher peaks than the low-sugar baseline across 516 matched logs (p<0.001).
  • ▸You expect a varietal difference — black plum vs. fresh tracked −1.6 mg/dL across 89 logs (low confidence) and pluot / yellow returned too few qualifying meals to characterize.
● How it fits your day

Calorie band and pairings (member-measured)

Per serving
49–988 kcal
Single-item plum logs average 49 kcal; light-carb meals containing plums average 193 kcal; very heavy carb builds average 988 kcal. Pairings and meal context drive most of the spread.
● Pair before
  • ▸Keep total meal carbs under 60g: light-carb plum meals averaged +31.6 mg/dL vs. +41.7 mg/dL for 70–110g builds — about a 10 mg/dL swing.
  • ▸Pair with yogurt or cheese: yogurt trimmed −2 mg/dL (n=121) and cheese trimmed −1 mg/dL (n=316) below the alone baseline.
● Pair after
  • ▸A 10–15 min walk after a mixed meal helps clear circulating glucose, especially relevant if the plum was part of a 60g+ carb build.
  • ▸If dinner included plums in a heavier meal, note that dinner plum logs averaged +36.5 mg/dL vs. +29.8 mg/dL at snack time (n=387 vs n=652) — favor snack-time eating when possible.
● Avoid pairing
  • ▸High-sugar meal contexts (≥20g sugar): these logs ran 22% above the low-sugar baseline across 516 matched meals (p<0.001).
  • ▸Eating plums with a 60g+ carb base: the high-carb modifier added +10 mg/dL on average across 273 matched logs (CI: [+7.73, +12.65] mg/dL).
● Quick definitions (click to expand)
mg/dL — milligrams per deciliter. The unit blood glucose is measured in. A rise of "+30 mg/dL above baseline" means blood sugar went up 30 units after the meal.
Glycemic Index (GI) — a 0–100 score for how fast a food raises blood sugar in lab tests. Under 55 = low, 56–69 = medium, 70+ = high.
Glycemic Load (GL) — GI adjusted for portion size. Under 10 = low, 10–19 = medium, 20+ = high.
CGM — Continuous Glucose Monitor. A wearable sensor that tracks blood glucose every few minutes. Signos members wear CGMs while eating meals they log.
● Related Foods: How plums compare to other low-GI fruits in the Signos cohort
Cherries Glycemic Index and Glucose Response
Cherries are plum's closest stone-fruit sibling — both low-GI, both eaten mostly fresh and alone in the cohort.
Apricot Glycemic Index and Glucose Response
Apricots track plums closely on GI and cohort behavior — another low-spike stone fruit, often paired with cheese or yogurt.
Peach Glycemic Index and Glucose Response
Peaches average +29.3 mg/dL across 3,266 single-item logs — slightly below plum, with a similar low-GI profile and fat-pairing pattern.
Apple Glycemic Index and Glucose Response
Apples average +31.5 mg/dL across 17,729 logs — close to plum's eaten-alone mean, with a wider modifier spread.
Track Your Plum Response with Signos →
See exactly how your glucose responds to fresh plums — alone, with yogurt, or in a mixed meal — with continuous CGM data.

Frequently Asked Questions

Methodology

This page draws on Signos production CGM data logged between March 2025 and April 2026, covering 2,152 logged meals containing plums across 948 unique members — among the smallest cohorts in the fruit tranche. Statistical comparisons use Welch's t-test on matched pairs; all modifier effects cited carry p<0.001 unless noted. Cohort filtering restricts to meals with a measured glucose rise between 0 and 100 mg/dL (ppgr_case='regular') to exclude outliers and sensor artifacts. We report mean peak glucose rise across a right-skewed distribution; the cohort median is +31 mg/dL vs. a mean of +33.9 mg/dL. Plum logs were identified via regex matching on logged food names; composite preparations (plum cake, plum tart, plum sauce, prunes, sugar plums, umeboshi) are explicitly excluded. A minimum of 30 matched logs is required for any pairing or form to appear; sub-cohorts with fewer qualifying meals are excluded from the builder.

Limitations

  • Cohort size is modest at 2,152 logs from 948 unique members — among the smallest in the Signos fruit tranche. Modifier-level sub-cohorts are correspondingly smaller and individual deltas should be read as directional rather than precise.
  • Self-reported portion sizes introduce measurement error — a logged 'medium plum' may vary meaningfully in actual weight and sugar content across varieties (Japanese, European, prune-plum).
  • Cohort skews health-motivated; Signos members are actively monitoring glucose, so average responses may skew lower than a representative population sample.
  • Black plum / damson sub-cohort is low-confidence (n=89); the −1.6 mg/dL delta vs. fresh plum is plausible but carries wide uncertainty and should not be cited as precise.
  • Yellow / mirabelle and pluot / plumcot variants returned fewer than 10 qualifying meals each and are excluded from the builder; the page cannot characterize their response.
  • Oatmeal and baked-dessert pairings (tart, cobbler, cake) each returned fewer than 20 qualifying logs and are excluded — the builder reflects fresh-eaten patterns, not baked preparations.
  • All findings are observational, not causal — confounders including concurrent medications, activity levels, and sleep quality are not controlled for.
● Get your own data

See your own plum response

Across 2,152 logged plum meals, the average peak was +33.9 mg/dL — but the IQR spans 24 mg/dL (p25: +20, p75: +44). Eaten alone, the cohort drops to +30 mg/dL. A heavy meal pushes peaks 32% higher across 273 matched logs (p<0.001). Yogurt trims 2 mg/dL, cheese trims 1 — small but real. Only a CGM tells you exactly where your personal response lands and which builds work best for your biology.

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