This is an, open label unblinded study recruiting 15 people with A-T and 15 age and gender matched controls. Each participant will have three study visits to the Clinical Research Centre at Ninewells hospital in Dundee - one at baseline, a second after 8 weeks of metformin and the final visit after eight weeks of pioglitazone. During each visit we will carry out a number of investigations to study the insulin resistance of A-T and how it responds to metformin and pioglitazone.