Food Intelligence · Breakfast

Raisin Bran Glycemic Index and Calculate Your Own Glucose Response

Across 129 single-item raisin bran logs, Signos members averaged a +54.1 mg/dL glucose peak — with 82.2% of responses topping +30 mg/dL. That's notably higher than oatmeal (+38.9 mg/dL) or generic cereal (+38.3 mg/dL). Add ≥15g of protein and the peak drops ~8.6%; load the bowl with ≥60g of carbs and it climbs another 23.5%.

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

● Powered by Signos cohort dataMedium confidence · n=129
The swap calculator below draws on 884 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.

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Meal Context
Pre-meal sequence
Activity after meal
Time of day
73
of 100
Signos Glucose Score
Very High Spike Risk
75% of members fall between +44 and +64 mg/dL
Predicted Curve · 3-hr window
1401001201401601800m30m60m90m120m150m180m+54
Peak
+54
mg/dL
Time in Range
83%
3hr window
Above 140
30m
danger zone
Swaps
0
applied
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● Key Findings · Does raisin bran spike blood sugar?

Yes — across 129 logged meals where members ate raisin bran alone, the average glucose peak was +54.1 mg/dL, with 82.2% of responses exceeding the +30 mg/dL threshold. In our single-item cohort of 129 raisin bran logs from 99 unique members, the median peak was +55 mg/dL and 78.3% of responses fell in the high-spike tier — above both oatmeal (+38.9 mg/dL) and generic cereal (+38.3 mg/dL) in the same breakfast comparison set. The raisins are the dominant driver: their concentrated sugars add fast-digesting fructose and glucose on top of the bran starch load. Three levers partially offset the response: a protein pairing (≥15g) cut the broader-cohort mean by ~8.6% across 312 matched meals (p<0.01), a fat pairing (≥15g) trimmed it ~7.7% across 139 matched meals (p<0.05), and high carb load (≥60g) pushed it 23.5% higher across 409 matched meals (p<0.01). These are observational findings, not causal.

  • 78.3% of single-item logs produced a high spike (>+35 mg/dL) — the highest high-spike rate of any food in the breakfast comparison set measured here.
  • High carb load (≥60g at the meal) amplified the peak by 23.5% vs. lighter builds (p<0.01, n=409 vs. n=48) — stacking a second carb source on top of raisin bran pushes the response into extreme territory.
  • Protein pairing (≥15g) cut the broader-cohort peak by ~8.6% across 312 matched meals (p<0.01) — the single most effective lever in the modifier table.
  • Raisin Bran Crunch averaged +55.4 mg/dL vs. +52.5 mg/dL for plain raisin bran (n=201 vs. n=683) — a +2.9 mg/dL premium for the extra crunch clusters and sweetening.
● Signos Rules

Three citable insights from this recipe's data

Rule 1
"The Raisin Penalty"
+54.1 mg/dL mean
Across 129 single-item logs, raisin bran averaged +54.1 mg/dL — 15 mg/dL higher than plain oatmeal (+38.9 mg/dL) and 16 mg/dL above generic cereal (+38.3 mg/dL) in the same breakfast cohort. The bran supplies some fiber buffering, but the raisins' concentrated sugar load overrides it for most members. The 78.3% high-spike rate in our distribution confirms this isn't a fringe response.
Rule 2
"The Carb-Load Penalty"
+23.5% peak
Across 409 matched meals where total carbs hit ≥60g, raisin bran's glucose response ran 23.5% higher than the lighter-carb baseline across 48 matched meals (p<0.01, CI: [+3.47, +17.13] mg/dL). Raisin bran eaten dry already sits near 55g carbs per cup — adding orange juice, toast, or a banana on the side crosses that threshold quickly. Keeping the bowl to a single serving with no high-carb sides is the most reliable way to stay in the lower response range.
Rule 3
"The Protein Discount"
−8.6% peak
Pairing raisin bran with ≥15g of protein cut the average peak by ~8.6% across 312 matched meals (p<0.01, CI: [−8.16, −1.39] mg/dL). That's roughly 4–5 mg/dL off the cohort mean — meaningful but modest against a +54 mg/dL baseline. Greek yogurt, a protein shake, or two eggs on the side are the most practical vehicles. Fat pairings (≥15g) showed a parallel −7.7% reduction across 139 matched meals (p<0.05), confirming that any macronutrient buffer helps.
● Curious about your own?

Curious how your body responds to raisin bran specifically?

Across 129 logged meals where members ate raisin bran alone, the average glucose peak was +54.1 mg/dL — but the IQR spans 30 mg/dL (p25: +40, p75: +70), meaning your personal response could land well above or below the cohort mean. Bowl size, milk choice, protein pairing, and your own metabolic baseline all shift the outcome. A CGM makes that variability visible in real time.

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Why this meal spikes

This meal stacks 3 independent spike drivers — together they account for +53 mg/dL.

Driver 1
Raisin sugar load (~18–20g added sugar per cup from dried fruit)
+15 mg/dL
Raisins are concentrated dried grapes — roughly 60–70% simple sugar by weight. They add fast-digest fructose and glucose on top of the bran starch, explaining why raisin bran (+54.1 mg/dL) runs ~15 mg/dL above oatmeal (+38.9 mg/dL) in the same breakfast comparison set.
Driver 2
Bran-flake starch (~35–40g net carbs per cup, minus raisins)
+38 mg/dL
The bran flakes themselves contribute a moderate starch load. The single-item mean of +54.1 mg/dL across 129 logs reflects both fractions together. Carb buckets show that lighter portions (0–40g total carbs, n=48) averaged +43.8 mg/dL vs. the medium bucket (40–70g, n=509) at +53.5 mg/dL — a +9.7 mg/dL escalation from one serving tier to the next.
Driver 3
Absence of protein or fat buffer (eating alone)
+5 mg/dL
Single-item logs (n=173, mean +55.3 mg/dL) ran higher than multi-item meals (n=711, mean +52.7 mg/dL) — a ~4.7% difference consistent with the protein and fat modifiers measured separately. A ≥15g protein pairing cut the broader-cohort response by ~8.6% across 312 matched meals (p<0.01).
● Which bucket are you in?

Some members spike +43.8 mg/dL. Others spike +56.1. 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 raisin bran is how far it outpaces other breakfast cereals in the cohort. At +54.1 mg/dL across 129 single-item logs, it sits 15 mg/dL above oatmeal and 16 mg/dL above generic cereal in the same comparison set — despite a GI of 61 that most people would read as 'moderate.' The gap is the raisins. Fiber cereal marketing is accurate about the bran fraction; it's just silent about what the raisins add on top.
Signos Data Science Team

Why this happens, physiologically

Across 129 logged meals where members ate raisin bran alone, the average glucose peak hit +54.1 mg/dL — with 78.3% of responses in the high-spike tier and only 7.0% in the low-spike range. Two fuel sources drive that response simultaneously: the bran-flake starch (roughly 35–40g net carbs per cup) and the raisins' concentrated simple sugars (~18–20g added sugar per cup). The bran supplies some viscous fiber that slows starch digestion marginally, but the raisins' fast-release fructose and glucose override that buffer for most members. In the broader cohort, a protein pairing (≥15g) cut peaks by ~8.6% across 312 matched meals (p<0.01) and a fat pairing (≥15g) trimmed them ~7.7% across 139 matched meals (p<0.05) — meaningful secondary brakes, but neither erases the underlying carbohydrate load. These effects are observational from matched-pair analysis, not controlled trials.

● Three mechanisms drive raisin bran's glucose range

Raisin sugar load, starch content, and carb-load escalation together explain the wide cohort spread from +44 to +56 mg/dL

  1. Mechanism 1
    +15 mg/dL vs oatmeal
    Raisin sugar penalty
    Raisin bran's single-item mean of +54.1 mg/dL is 15 mg/dL above oatmeal (+38.9 mg/dL) in matched breakfast logs. Dried raisins are ~60–70% simple sugar by weight, adding a fast-digest sugar spike on top of bran starch.
  2. Mechanism 2
    +23.5%
    High carb load
    Meals with ≥60g total carbs spiked 23.5% above the lighter-carb baseline (p<0.01, n=409 vs. n=48, CI: [+3.47, +17.13] mg/dL). A single cup of raisin bran already approaches 55g carbs — one extra carb side crosses the threshold.
  3. Mechanism 3
    −8.6%
    Protein buffer
    A ≥15g protein pairing cut the broader-cohort response by ~8.6% across 312 matched meals (p<0.01, CI: [−8.16, −1.39] mg/dL). Protein slows gastric emptying, blunting the rate of glucose absorption from both starch and raisin sugars.
● Fit Check
Raisin bran lands near the top of the breakfast spike ladder — the raisins make it a high-sugar cereal despite the fiber branding. What you pair it with matters, but the baseline is high.
This is for you if
  • You pair the bowl with ≥15g protein (Greek yogurt, protein shake, two eggs) — matched logs cut the broader-cohort response by ~8.6% across 312 meals (p<0.01).
  • You add berries instead of extra fruit — 48 matched logs with berries averaged +45.0 mg/dL vs. +53.3 mg/dL for the no-extra-fruit baseline (−8 mg/dL, low confidence).
  • You keep total meal carbs under 40g — the light-carb bucket (n=48) averaged +43.8 mg/dL vs. +53.5 mg/dL in the medium bucket (40–70g, n=509).
  • You choose almond milk over skim milk — almond milk pairings (n=51) averaged +51.8 mg/dL vs. +56.8 mg/dL for skim/2% (n=41), a modest but consistent difference.
Not for you if
  • You eat raisin bran alone at breakfast — single-item logs (n=173) averaged +55.3 mg/dL, with 85.0% of responses above +30 mg/dL.
  • You stack a second carb source (juice, toast, banana) on top — ≥60g total carb meals spiked 23.5% higher than lighter builds (p<0.01, n=409 vs. n=48).
  • You're targeting blood-sugar stability — 78.3% of single-item logs landed in the high-spike tier (>+35 mg/dL), the highest distribution share in the breakfast comparison set.
  • You're choosing raisin bran over plain oatmeal for its fiber benefit — the single-item mean of +54.1 mg/dL is 15 mg/dL above oatmeal's +38.9 mg/dL in matched logs.
● How it fits your day

Calorie band and pairings (member-measured)

Per serving
210–802 kcal
Light-carb raisin bran meals (0–40g carbs, n=48) averaged 210 kcal; very heavy builds (110g+ carbs, n=87) averaged 802 kcal. Toppings and pairings drive most of the calorie spread.
Pair before
  • Add a ≥15g protein pairing (Greek yogurt, two eggs, protein shake) — matched logs cut the broader-cohort response by ~8.6% across 312 meals (p<0.01).
  • Keep total meal carbs under 40g: the light-carb bucket averaged +43.8 mg/dL vs. +53.5 mg/dL for the medium bucket (40–70g) — a 22% escalation from one tier to the next.
Pair after
  • A 10–20 min walk within 30 min of eating helps clear circulating glucose — especially relevant given 82.2% of single-item raisin bran logs exceed +30 mg/dL.
  • Avoid stacking sweet beverages or dessert after the bowl — the cereal already carries 18–20g of raisin-derived sugar; additional fast-carb sources compound the load.
Avoid pairing
  • Orange juice, toast, or a banana on the side: these push total carbs past 60g, the threshold where the cohort spike rate jumps 23.5% above lighter builds (p<0.01, n=409).
  • Skim or 2% milk as the default: at +56.8 mg/dL (n=41), skim tracked 5 mg/dL above the no-milk baseline and 5 mg/dL above almond milk in matched logs.
● 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: Raisin bran sits at the high end of the breakfast spike ladder — here's how it compares to adjacent cereals and whole foods, and how to track your own response.

Frequently Asked Questions

Methodology

This page draws on Signos production CGM data logged between Mar 2025 and Apr 2026, covering 884 meals containing raisin bran across 454 unique members (broader cohort), with a single-item sub-cohort of 129 meals (99 unique members) where raisin bran was logged without other foods. The single-item sub-cohort is the page primary; its mean peak of +54.1 mg/dL and 82.2% above-30 rate are the headline figures. Statistical comparisons use Welch's t-test on matched pairs; modifier effects are cited with p-values as noted — the protein and fat modifiers carry p<0.01 and p<0.05 respectively. Cohort filtering restricts to meals with a measured glucose rise between 0 and 100 mg/dL (ppgr_case='regular'). Raisin bran logs were identified via regex matching on the canonical phrase 'raisin bran'. The single-item cohort (n=129) meets the medium-confidence threshold (≥100 meals) but not the high-confidence threshold (≥500); estimates should be treated as directionally reliable but carry wider uncertainty than high-confidence cohorts. A minimum of 30 matched meals is used for modifier slots in the recipe builder at this cohort size.

Limitations

  • Single-item cohort is n=129 (medium confidence) — estimates are directionally reliable but carry wider uncertainty than high-N cohorts; the IQR of 30 mg/dL (p25: +40, p75: +70) signals substantial individual variability.
  • Self-reported portion sizes introduce noise — a 'cup' of raisin bran can vary meaningfully in weight and raisin density between brands and member pours.
  • Cohort skews health-motivated; Signos members are actively monitoring glucose, so average responses may understate what a general-population sample would show.
  • Milk and fruit pairing sub-cohorts are low-confidence (n=41–133); the reported deltas are directional signals, not precise estimates — treat with caution.
  • Raisin Bran Crunch and plain Raisin Bran are different formulations with different sugar densities; the +2.9 mg/dL delta between them (n=201 vs. n=683) is medium-confidence.
  • All findings are observational from matched-pair analysis, not controlled trials — confounders including concurrent medications, activity levels, and sleep quality are not controlled for.
● Get your own data

See your own raisin bran response

Across 129 logged meals where members ate raisin bran alone, the average glucose peak was +54.1 mg/dL — one of the highest single-item means in the breakfast category. But the IQR spans 30 mg/dL (p25: +40, p75: +70), so your biology matters as much as the food. Protein pairing cuts the broader-cohort response ~8.6%; keeping carbs light holds the mean to +43.8 mg/dL. Only a CGM tells you exactly where you fall — and which build keeps your curve in range.

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