● Food Intelligence · Beverage
Across 35,570 logs of coffee consumed alone, members averaged just +21.7 mg/dL (median +17) — and black coffee carries GI 0 / GL 0, meaning the bean itself contributes no digestible carbs. The +25.4 mg/dL average across the broader 209,577-log cohort is almost entirely driven by what's added to the cup or eaten with it: a pastry pairing pushes the peak to +38.2 mg/dL, while a sweetener alone runs +34.2 mg/dL.
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No — black coffee is GI 0 / GL 0, and across 35,570 single-item logs members averaged just +21.7 mg/dL with 58.4% of responses landing under +20 mg/dL. Coffee is the largest beverage cohort in the atlas — 209,577 logs from 16,505 unique members. Black brewed coffee carries no digestible carbohydrate, so the modest +21.7 mg/dL single-item average is essentially noise plus whatever splash of cream most members default to. The signal lives in the build: coffee paired with a bagel or donut averaged +38.2 mg/dL (+14 mg/dL over the alone-baseline of +24.5, n=6,787), and a sweetened cup ran +34.2 mg/dL on its own. Inversely, eggs-and-bacon pairings barely moved the needle — just +2 mg/dL above the alone-baseline across 50,117 logs.
Some members spike +21.7 mg/dL. Others spike +38.6. The only way to know how you'll spike is to measure with a Signos CGM.
Coffee is, biochemically, a near-zero-carbohydrate beverage — black brewed coffee carries a published GI of 0 and GL of 0. So the +21.7 mg/dL average we measure across 35,570 single-item logs is almost entirely a function of what members add to the cup (a cream splash, a flavored creamer, a teaspoon of sugar) rather than the coffee itself. In the broader 209,577-log cohort, three levers drive the residual signal: in-cup sweetener (+10.9 mg/dL above the black anchor across n=490 sweetened logs), carb-pairing at the meal level (the dominant force — pastry and sandwich pairings each added +14 mg/dL across n=6,787 and n=2,146), and morning timing (peaks ran 7.8% lower before 10 a.m. across 154,171 logs, CI: −2.35 to −1.85 mg/dL). The mechanisms are observational, not yet causal — but the pattern is clean: the coffee is glucose-inert, and what surrounds it isn't.
This page draws on 35,570 single-item Coffee logs (meals where coffee was logged alone, no pairings) from 6,603 unique Signos members, plus a broader 209,577-meal cohort spanning all meal contexts where coffee appeared — the largest beverage cohort in the atlas, drawn from 16,505 unique members. Data were filtered to postprandial glucose responses (PPGR) between 0 and 100 mg/dL to exclude sensor artifacts and implausible readings. Modifier effects were estimated using Welch's t-test on matched pairs against a defined baseline; all reported effects carry p<0.001 unless noted. Black coffee carries a published glycemic index of 0 and glycemic load of 0 — the calculator's form-slot anchors are zeroed accordingly, with the cohort means preserved per option for transparency. We report mean glucose peak across a right-skewed distribution — the median single-item spike of +17 mg/dL is several mg/dL lower than the mean of +21.7 mg/dL, which is typical for this type of data. Any carb-pair pairing slot requires at least 100 matched meals before it appears in the recipe builder.