Cohort profile: the Nanjing Diabetes Cohort database - a population-based surveillance cohort.

Purpose: To study epidemiology, complications, risk factors, clinical course and treatment patterns of diabetes, the Nanjing Diabetes Cohort (NDC) was established using anonymised electronic health records from 650 hospitals and primary care since 2020. This cohort provides valuable data for researchers and policy-makers focused on diabetes management and public health strategies.

Participants: Diabetes was defined as having inpatient or outpatient encounters with a diagnosis of diabetes International Classification of Diseases-9/10 codes, any use of insulin or oral hypoglycaemic drugs, or one encounter with haemoglobin A1C >4.8 mmol/mol or 6.5%. Patients with diabetes have been continuously enrolled on hospitals and primary care in Nanjing since 2020. Demographic, medications and comorbidities data were extracted from clinical notes, diagnostic codes, labs, prescriptions and vital signs among different types of diabetes.

Findings To Date: The NDC consisted of 1 033 904 patients from 1 January 2020 to 31 December 2022, the majority were male (50.62%) and from the Gulou district (30.79%). The clinical characteristics and medication usage of patients with type 1 diabetes, type 2 diabetes, gestational diabetes and other diabetes were assessed. The prevalences of hypertension, ischemic heart disease, and cerebrovascular disease were 49.72%, 17.85% and 24.90%, respectively.

Future Plans: NDC will annually enrol eligible patients and include socioeconomic data in future updates. The data of NDC are maintained by the Department of Medical Informatics at Nanjing Medical University.