Effects on Glycemia and Insulinemia of Different Grape Varieties

Assessment of the Effect of Different Varieties of Grapes on Postprandial Glycemia and Insulinemia

The goal of this intervention study is to examine the glucose increase in blood, during 2 hours after consuming different varieties of grapes, in men and women with normal or excess body weight. The main question it aims to answer is:

can a variety of red grape reduce the glucose curve compared to a reference variety?

Participants will have to attend the Center for nutrition research facilities in three occasions, fasted for at least 8 hours. Once there, they will be measured and monitored. A canula will be inserted and once they finish eating 300g of grapes, blood extractions will be performed at minutes 15, 30, 60, 90 and 120.

The main purpose of this study is to evaluate how the glucose and insulin curves develop after consuming different grapes varieties. Still, we also want to evaluate how the serum metabolome changes with the three varieties after 120 minutes. Therefore, a metabolomic study will be done in samples of volunteers at this time point.

The intervention is longitudinal and in three arms (one per variety). Due to the harvest of the different varieties, it cannot be crossover, but each subject will consume the three varieties.

At each visit, the subjects will undergo the same schedule:

• Arrival in a fasting state of at least 8 hours.
• Insertion of cannula and extraction of fasting samples
• Consumption of approximately 300 g of grapes (50 g of Carbohydrates).
• Extraction of blood samples at 15, 30, 60, 90 and 120 minutes.

Inclusion Criteria:

• Baseline glycaemia between 70 and 100 mg/dL
• BMI between 18.5 kg/m2 and 29.9 kg/m2.
• Absence of disease or alterations related to gastrointestinal status.
• Signed written informed consent.

Exclusion Criteria:

• Glycaemic levels out of the reference inclusion criteria (below 70 or over 100 mg/dL)
• Subjects presenting BMI out of the limits set.
• Subjects with unstable body weight the three months prior the start of the study (+/- 3 Kg)
• Subjects not able to attend the preestablished visits
• Women pregnant or lactating
• Subjects undergoing pharmacological treatment