Seasonal Variations in the Achievement of Guideline Targets for HbA_1c, Blood Pressure, and Cholesterol Among Patients With Type 2 Diabetes: A Nationwide Population-Based Study (ABC Study: JDDM49).

Abstract

Precise monthly achievement rates for reaching guideline targets for HbA_1c, blood pressure (BP), and lipid levels remain unknown. We evaluated achievement rates on a monthly basis in persons with type 2 diabetes mellitus (T2DM) and explored related factors. This retrospective study initially analyzed data on 104,601 persons with T2DM throughout Japan. Patients whose HbA_1c, BP, and LDL cholesterol were measured ≥12 times during a 24-month period were included. We evaluated monthly achievement rates. Achieved targets were defined as HbA_1c <7%, BP <130/80 mmHg, and LDL cholesterol <100 mg/dL. Achievement of all targets was expressed as the "all ABC achievement." A total of 4,678 patients were analyzed. The achievement rates of all ABC, HbA_1c, BP, and LDL cholesterol were lowest in winter, with those for systolic BP (SBP) being particularly low (all ABC, summer 15.6%, winter 9.6%; HbA_1c, 53.1%, 48.9%; SBP, 56.6%, 40.9%; LDL cholesterol, 50.8%, 47.2%). In winter, age ≥65 years (odds ratio 0.47 [95% CI 0.34-0.63]) was independently related to decreased achievement rates for SBP, BMI ≥25 kg/m² (BMI 25-30 kg/m², 0.45 [0.29-0.70]; BMI ≥30 kg/m², 0.35 [0.22-0.57]), and diabetes duration ≥10 years (0.53 [0.37-0.76]) were independently related to lower achievement rates for HbA_1c. Insulin use and sulfonylurea use were independently associated with the decreased all ABC achievement rates in both summer and winter. The all ABC achievement rate for guideline targets changed on a monthly basis. Seasonal variations in the all ABC achievement rate should be considered when managing T2DM in ordinary clinical practices.