Blood samples from the tail vein were collected in EDTA-coated microvettes (Sarstedt) at 0, 10, and 30 minutes during OGTT and after 5-hour fasting (18 (link)). Plasma was separated from whole blood by centrifugation at 4226g for 10 minutes at 4°C. Insulin and proinsulin were analyzed using mouse ultrasensitive insulin ELISA (ALPCO).
Free full text: Click here