Limiting post-meal blood sugar spikes appears worthwhile, even for people without diabetes, although the evidence for most interventions is still small-scale. Walking immediately after a meal has the best and most practical evidence base. Sweetener drinks offer no benefit if eating behaviour afterwards does not change.
Post-meal blood sugar spikes vary considerably between people, even without diabetes. Research using continuous glucose monitors in 25 healthy individuals shows that those who break down glucose more slowly experience higher spikes, and that there is also a day-night rhythm in blood sugar that differs markedly from person to person1. 'Normal' blood sugar is therefore not a fixed benchmark that applies equally to everyone.
The intervention with the strongest and most practically accessible evidence is walking immediately after a meal. A meta-analysis (116 participants in total, small but consistent) showed a moderate effect: walking as soon as possible after eating significantly reduced the blood sugar spike, with a standardised mean difference of 0.55. Walking before a meal had no measurable effect. The studies had a high risk of bias, so the evidence is promising but not definitive2.
There are also positive indications for drinking mulberry leaf tea before meals every day for two weeks. In a study of 31 healthy and pre-diabetic participants, blood sugar variability decreased significantly and no side effects such as low blood sugar or abnormal liver and kidney values occurred. The active compound in the tea inhibits carbohydrate digestion. Long-term safety has not, however, been investigated3.
Drinks containing sweeteners, such as those with aspartame, monk fruit or stevia, appear at first glance to be a smart swap for sugar-sweetened drinks. However, in a controlled study people ate more at the next meal, which fully compensated for the lower blood sugar spike. Over a three-hour period there was no difference in blood sugar or insulin compared with regular sugar4. Simply switching to sweeteners therefore probably offers little benefit if eating behaviour afterwards does not change.
Powdered cinnamon dissolved in water may reduce the post-meal blood sugar spike, but this has only been demonstrated in patients with diabetes in a small study (19 participants) and did not work when taken as a capsule5. Oleuropein, a compound from olives, reduced the blood sugar spike in healthy individuals, but only at a low sugar dose (25 grams), not with bread, and one author is affiliated with a company that sells oleuropein6. Isomaltulose as a sugar substitute produced a statistically significant but modest reduction in blood sugar 60 minutes after the meal in patients with diabetes; two of the three authors are affiliated with a manufacturer of this product7. All of these interventions are too early in the research process to base strong practical recommendations on them, certainly for healthy individuals.
The biological plausibility that high blood sugar spikes are unfavourable in the long term is supported by research showing that the insulin spike after a meal prompts immune cells to adhere more strongly to blood vessel walls, both in mice and in healthy humans. What this means for long-term health, however, cannot be determined from that research8.
Eight studies used: one meta-analysis on walking (n=116), one controlled study on sweeteners, one small RCT on cinnamon (n=19), one mechanistic study on insulin and immune cells, one small study on oleuropein in healthy volunteers (n=small, commercial interest), one observational CGM study (n=25), one RCT on mulberry leaf tea (n=31), and one meta-analysis on isomaltulose in patients with diabetes (commercial interest). Most human studies are small; walking has the broadest evidence base.