The same meal, a bigger night-time spike
An identical meal tends to produce a larger and longer glucose rise when eaten late at night than in the morning. Studies of meal timing have reported evening glucose responses that are substantially greater than morning ones, with figures often in the range of roughly 30 to 50 percent higher depending on the protocol. The driver is circadian: insulin sensitivity falls in the evening and melatonin rising near bedtime can suppress insulin secretion.
This is why a heavy late dinner or midnight snack can blunt overnight metabolic recovery more than the same food earlier in the day.
Practical reading of the timing effect
The takeaway is not that late eating is forbidden but that shifting more calories earlier may ease glucose handling, particularly for people with impaired glucose tolerance. The exact percentage difference varies by individual, meal composition, and sleep timing, so the cited range should be read as indicative rather than precise.
This is general educational information, not medical advice. Anyone managing diabetes or prediabetes should discuss meal timing with a qualified professional.