How to diagnose and classify diabetes in primary health care: Lessons learned from the Diabetes Register in Northern Sweden (DiabNorth)

Objective. The objective was to create a diabetes register and to evaluate the validity of the clinical diabetes diagnosis and its classification. Design. The diabetes register was created by linkage of databases in primary and secondary care, the pharmaceutical database, and ongoing population-based health surveys in the county. Diagnosis and classification were validated by specialists in diabetology or general practitioners with special competence in diabetology. Analysis of autoantibodies associated with type 1 diabetes was used for classification. Setting. Primary and secondary health care in the county of V sterbotten, Sweden. Patients. Patients with diabetes (median age at diagnosis 56 years, inter quartile range 50-60 years) who had participated in the V sterbotten Intervention Programme (VIP) and accepted participation in a diabetes register. Results. Of all individuals with diabetes in VIP, 70% accepted to participate in the register. The register included 3256 (M/F 1894/1362) diabetes patients. The vast majority (95%) had data confirming the diabetes diagnoses according to WHO recommendations. Unspecified diabetes was the most common (54.6%) classification by the general practitioners. After assessment by specialists and analysis of autoantibodies the majority were classified as type 2 diabetes (76.8%). Type 1 diabetes was the second largest group (7.2%), including a sub-group of patients with latent autoimmune diabetes (4.8%). Conclusion. It was concluded that it is feasible to create a diabetes register based on information in medical records in general practice. However, special attention should be paid to the validity of the diabetes diagnosis and its classification.