SCOPE: It is unclear which factors influence the inter-individual variations of postprandial changes in blood glucose. Therefore, we investigated whether the habitual diet is associated with the postprandial glycemic response. METHODS AND RESULTS: Clinical and metabolic data from healthy adults (young adults with 18 - 25 years, middle-aged adults with 40 - 65 years, and older adults with 75 - 85 years) at baseline and during an oral glucose tolerance test (OGTT) was collected. Habitual diet was assessed by a food frequency questionnaire and two 24-hour food lists. Regression models were fitted to examine associations between habitual diet and glucose incremental area under the curve (iAUCmin ). The intake of cereals and cereal products is negatively associated with glucose iAUCmin (p = 0.002) in the total cohort (N = 459, 50 % women, 55 ± 21 years, BMI 26 ± 5 kg/m2 ). Total carbohydrate intake and the intake of cereals and cereal products predict glucose iAUCmin in the total cohort. Up to 9 % of the variance in the glycemic response was explained by the respective dietary parameters identified in the models of the specific age groups. CONCLUSION: These findings suggest, that there are age-specific diet-related effects on postprandial glucose response. Of all investigated dietary parameters, the usual intake of cereals and cereal products seems to play a greater role in postprandial glucose metabolism in more than one age group. Further research is needed, to establish how diet can be optimized based on age and the postprandial response. This article is protected by copyright. All rights reserved.