title: [Evaluation of seasonal changes in hemoglobin A1c in diabetic patients].
abstract: In order to evaluate seasonal changes in hemoglobin A1c (HbA1c) values, we examined HbA1c values among 34,590 patients in 2010, and calculated the monthly average of HbA1c values through the year. HbA1c values were the highest in March and the lowest in October with a difference of 0.30%. The similar annual pattern was observed in HbA1c values from 2006 to 2009. Then we selected 453 diabetic patients whose treatment did not change through the year, and calculated average HbA1c values in four seasons each. There were also significant seasonal changes in diabetic patients, which were the highest in the spring and the lowest in the autumn, especially found in patients with insulin therapy. These effects may be caused by cold climate, decreased physical activity, over food intake and body weight gain in the winter. These seasonal changes in HbA1c should be concerned in the case of health service research, clinical trials and evaluation of the effects of medical treatment.
authors.affiliation: Clinical Laboratory Medicine, Wakayama Medical University, Wakayama 641-8509, Japan. machi@wakayama-med.ac.jp
authors.forename: Machi
authors.initials: M
authors.lastname: Furuta
authors.forename: Ryuya
authors.initials: R
authors.lastname: Tomisaka
authors.forename: Akiko
authors.initials: A
authors.lastname: Yamana
authors.forename: Shuhei
authors.initials: S
authors.lastname: Morita
authors.forename: Minoru
authors.initials: M
authors.lastname: Ueyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Imanishi
authors.forename: Chihaya
authors.initials: C
authors.lastname: Ooishi
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Hara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ooishi
authors.forename: Tokio
authors.initials: T
authors.lastname: Sanke
mesh_terms: D000368:Aged; D003920:Diabetes Mellitus / Q000097:blood* / Q000178:diet therapy / Q000188:drug therapy; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006456:Hemoglobinuria / Q000652:urine; D006801:Humans; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D012621:Seasons
chemical_list: D006442:Glycated Hemoglobin; D007328:Insulin