This study will recruit non-diabetic individuals - 15 cases (people with A-T) vs 15 age and gender matched controls - in a crossover design. Participants will be 18 - 30 years of age. This age group is most realistic for recruiting patients with "classic", as opposed to "mild variant" A-T, as people with classic A-T rarely survive to their 30s. Exclusion of individuals with other milder forms of A-T will provide a more detectable difference between the two cohorts. Participants will be of white European descent, as this will narrow the genetic differences between individuals. Ethnic origin also has an effect on an individual's insulin resistance, therefore all the participants should be of the same ethnicity.