Aim To use general practice-level data for England, available through the National Diabetes Audit, and primary care prescribing data to identify prescription treatment factors associated with variations in achieved glucose control (HbA 1c ).Methods General practice-level National Diabetes Audit data on Type 1 diabetes, including details of population characteristics, services, proportion of people achieving target glycaemic control [HbA 1c ≤58 mmol/mol (7.5%)] and proportion of people at high glycaemic risk [HbA 1c >86 mmol/ml (10%)], were linked to 2013-2016 primary care diabetes prescribing data on insulin types and blood glucose monitoring for all people with diabetes.