● Food Intelligence · Fruit
Across 1,096 single-item logs of blackberries from 771 Signos members, the average glucose peak was +28.8 mg/dL — well below what GI 39 might suggest, owing to blackberries' high-fiber load. Pair them with yogurt and the peak holds at +27.2 mg/dL across 5,783 logs; serve them on oatmeal and the average climbs to +40.7 mg/dL.
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No — not meaningfully for most members. Across 1,096 single-item logs, blackberries averaged just +28.8 mg/dL, with 39% of responses staying under 20 mg/dL. Across our cohort of 1,096 single-item blackberry logs from 771 unique members, the mean glucose peak was +28.8 mg/dL with a median of +25 mg/dL — a low-to-moderate response consistent with the published GI of 39. Three levers shape the rest of the range. Total meal carb load is the dominant one: in the broader 19,139-log cohort, meals with ≥60g of carbs ran 45% higher than low-carb meals (n=2,645). Pairing context matters too — yogurt holds the peak at +27.2 mg/dL (n=5,783), while oatmeal pushes it to +40.7 mg/dL (n=450). The IQR is wide (24 mg/dL: p25 +15, p75 +39), so individual response still varies a lot.
Some members spike +26.6 mg/dL. Others spike +42. The only way to know how you'll spike is to measure with a Signos CGM.
Blackberries produce a mean peak of +28.8 mg/dL across 1,096 single-item logs — lower than what GI 39 alone would predict, owing to their high-fiber, low-net-carb profile. The IQR spans 24 mg/dL (p25 +15, p75 +39), so individual response varies meaningfully even within a low-spike food. Three levers explain most of the range. First, total meal carb load dominates: in the broader 19,139-log cohort, meals carrying ≥60g of carbs ran 45% above the low-carb baseline (n=2,645, p<0.001), with a 58% escalation from light-carb meals (+26.6 mg/dL) to very-heavy ones (+42 mg/dL). Second, pairing context shifts the peak — yogurt holds it at +27.2 mg/dL (n=5,783), while oatmeal pushes it to +40.7 mg/dL (n=450). Third, fat pairings (≥15g) trimmed the response by ~7% across 10,147 matched logs. These effects are observational from matched-pair Welch's t-tests, not controlled trials.
This page draws on three nested cuts of the Signos production PPGR cohort. The page-primary number — cited everywhere above the swap calculator — comes from the single-item cohort: 1,096 logs where blackberries were eaten alone, from 771 unique members, with a mean peak of +28.8 mg/dL, a median of +25 mg/dL, and an IQR of p25 +15 to p75 +39 mg/dL. The broader cohort (19,139 logged meals containing blackberries in any form, 4,595 unique members, mean +29.3 mg/dL) describes what real-world blackberry meals look like with all their pairings included; we cite it only here in methodology and in the modifier table. The swap calculator's matched-pair table draws on the same broader cohort and powers the per-option Ns shown in the modifier slots. Data was filtered to meals with a measured glucose rise between 0 and 100 mg/dL (ppgr_case='regular') to exclude outliers and sensor artifacts. Statistical comparisons between modifier groups use Welch's t-test on matched pairs; all reported effects reach p<0.001. Blackberry logs were identified via a regex match on "blackberry" / "blackberries" with composite-dish exclusions (cake, pie, tart, cobbler, sauce, syrup, jam) reserved for separate carb-pair slots. A minimum of 100 matched meals was required for any pairing to appear in the recipe builder.