Acute glycemic responses to meal-associated alcoholic beverages and ethanol in adults with type 2 diabetes: a systematic review

Background A lower next-morning glucose value after evening alcohol consumption may be mistaken for improved diabetes control, but direct evidence for this observation and for preceding nocturnal hypoglycemia is limited. We evaluated acute postprandial, overnight, and next-morning glycemic responses to alcoholic beverages or ethanol in adults with type 2 diabetes. Methods PubMed, Web of Science Core Collection, the Cochrane Library, MEDLINE with Full Text, SPORTDiscus with Full Text, eBook Collection, OpenDissertations, and Embase were searched from inception to 28 August 2026. Acute alcohol-free comparisons and active comparisons between alcohol-containing beverages were eligible, with the latter classified only as beverage-composition evidence. Risk of bias was assessed with RoB 2 or ROBINS-I, and findings were synthesized narratively. Results Fifteen small, heterogeneous studies were included. Meal-associated exposures did not consistently reduce postprandial glucose. Two active-beverage studies reinforced the importance of beverage composition: sweet versus dry wine and sherry produced no significant difference in evening glucose AUC, while glucose increased after carbohydrate-containing beer and sake but remained near baseline after carbohydrate-free shochu in a fasting comparison. Neither study estimated alcohol versus no alcohol. Only one alcohol-versus-control crossover study (n = 16) reported lower next-morning glucose (paired difference, −0.7 ± 0.2 mmol/L); the value was not hypoglycemic and the finding was not independently replicated. No study documented that a lower morning value was preceded by nocturnal hypoglycemia, and none reported contemporary overnight continuous-glucose-monitoring metrics sufficient to exclude brief or asymptomatic events. Conclusion Very-low-certainty evidence does not support alcoholic beverages or ethanol as a strategy to improve acute glycemia or lower morning glucose. Whether evening consumption contributes to delayed nocturnal hypoglycemia remains unresolved, especially in insulin- or insulin-secretagogue-treated populations. Systematic review registration https://www.crd.york.ac.uk/prospero/view/ , identifier CRD420261474632.