Postprandial study protocol and assessment of insulin sensitivity
Cohort 2 subjects attended our Clinical Research Facility at 09:00 hours after an overnight fast. The standard OFTT meal comprised fresh cream with 40% (weight by volume; w/v) fat emulsion (polyunsaturated:saturated fat ratio of 0.10) that contained 0.001% (w/v) cholesterol and 3% (w/v) carbohydrates, and had a total energy content of 3700 Kcal/L13. The fresh cream was given at a dose of 50g fat and 3.75g glucose/m2 body surface (approximately 200ml). Subjects were allowed up to 10 minutes to consume the meal. During the test, participants remained supine and were only allowed to drink mineral water. Blood samples were obtained at 0 (fasting baseline), 30, 60, 120, 180 and 240 minutes after consuming the meal, collected into sodium EDTA (2 mg/mL) then centrifuged immediately for 15 min at 800 × g  at 4 °C. Plasma was separated and stored in aliquots at −80 °C until analysis. The areas under the curves (AUC) for triglycerides and complement components were calculated using the trapezoid method.
On a separate day, after an overnight fast, subjects in cohort 2 underwent basal sampling for measurement of lipids and testosterone. Subjects subsequently underwent a standard 75g oral glucose tolerance test (OGTT). Glucose and insulin were measured at 0, 30, 60, 90 and 120 minutes. The AUCs for insulin and glucose were calculated using the trapezoid method. The homeostatic model assessment method was also used to estimate insulin resistance (HOMA-IR).