The Health Improvement Network (THIN) is an electronic medical records database that is representative of the broader U.K. population (http://www.thin-uk.com/). Data available in THIN include demographic information, medical diagnoses, lifestyle characteristics, and other measurements, including glycosylated hemoglobin (HbA1c) and BMI. The software automatically codes medical diagnoses at entry using the Read Coding System (21). THIN also records new and repeat prescriptions written by the general practitioner as the computerized record is used to generate these prescriptions.