Project 467010

Greater intake of dairy products has been associated with lower type 2 diabetes(T2D) risk. This inverse association is particularly strong when circulating 15:0, 17:0 and t16:1n-7 fatty acid(FA) levels are used as biomarkers of dairy fat intake. Evidence for an association between these biomarkers, and impaired insulin sensitivity and β-cell function remain inconclusive. No study has assessed the relationship between insulin sensitivity and these biomarkers in adipose tissue, reflecting long-term dietary FA intake. Dairy is the main food source of branched-chain FAs, promising biomarkers of dairy intake. The aims areto determine the association between established and potential biomarkers of dairy fat intake and clamp-based measures of insulin sensitivity, and to examine the potential for branched-chain FA in adipose tissue and serum as biomarkers of dairy fat intake. The proposed study is a cross-sectional cohort of lean, overweight and obese adults without or with prediabetes or T2D. Non-diabetic volunteers underwent a 75-g oral glucose tolerance test. Volunteers completed a 24-hour food recall and a 3-day food diary preceding the hyperinsulinemic-euglycemic clamp. Fasting serum samples and subcutaneous adipose tissue biopsies were collected. Gas chromatography mass spectrometry will be used for targeted quantitation of FA biomarkers of dairy fat in serum lipid fractions and adipose tissue. Linear regression models will be used to examine the association between FA biomarkers of dairy fat intake and insulin sensitivity. We expect FA biomarkers will be positively associated with insulin sensitivity, and branched-chain FAs will reflect dairy fat intake. This study will clarify the association between dairy fat intake and insulin sensitivity.