title: Seasonal variation in hemoglobin a1c in korean patients with type 2 diabetes mellitus.
abstract: A seasonal variation of glucose homeostasis in humans has been reported in various geographic regions. In this study, we examined seasonal variations in hemoglobin A1c (HbA1c) in patients with type 2 diabetes living in Korea. We analyzed 57,970 HbA1c values from 4,191 patients and the association of these values with ambient temperature for 3.5 yr. Overall, HbA1c exhibited its highest values from February to March and its lowest values from September to October (coefficient for cos t = -0.0743, P = 0.058) and the difference between the peak and nadir in a year was 0.16%-0.25%. A statistically significant seasonal variation was observed in the patients who were taking oral anti-diabetic drugs (OADs) without insulin treatment (coefficient for cos t = -0.0949, P < 0.05). The Spearman correlation coefficient between daily HbA1c values and the corresponding 3-month moving average ambient temperature was -0.2154 (95% confidence interval [CI]: -0.2711, -0.1580; P < 0.05). In conclusion, HbA1c values exhibited a seasonal variation in Korean patients with type 2 diabetes, with the highest values during the cold season, particularly in those who were treated with OADs, which should be taken into account in clinical practice for stable glucose control during the cold season.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yoon Ji
authors.identifier: 0000-0001-9730-4120
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, Seoul, Korea.
authors.forename: Seongkeun
authors.identifier: 0000-0002-4868-9404
authors.initials: S
authors.lastname: Park
authors.affiliation: Interdisciplinary Program for Bioengineering, Graduate School, Seoul National University, Seoul, Korea.
authors.forename: Wangjin
authors.identifier: 0000-0002-7741-5525
authors.initials: W
authors.lastname: Yi
authors.affiliation: Department of Clinical Pharmacology and Therapeutics Seoul National University College of Medicine and Hospital, Seoul, Korea.
authors.forename: Kyung-Sang
authors.identifier: 0000-0003-0921-7225
authors.initials: KS
authors.lastname: Yu
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Tae Hyuk
authors.identifier: 0000-0002-7975-2437
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Tae Jung
authors.identifier: 0000-0002-5078-6123
authors.initials: TJ
authors.lastname: Oh
authors.affiliation: Department of Biomedical Engineering, Seoul National University, Seoul, Korea.
authors.forename: Jinwook
authors.identifier: 0000-0002-9424-9944
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Young Min
authors.identifier: 0000-0002-2331-6126
authors.initials: YM
authors.lastname: Cho
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D044466:Asian People; D001424:Bacterial Infections / Q000517:prevention & control; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000188:drug therapy; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D056910:Republic of Korea; D012621:Seasons; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin
keywords: Diabetes Mellitus, Type 2; Hemoglobin A, Glycosylated; Seasonal Variation
references.citation: Am J Clin Nutr. 2004 May;79(5):820-5
references.pmid: 15113720
references.citation: Clin Chem. 2000 Apr;46(4):551-9
references.pmid: 10759480
references.citation: J Neuroendocrinol. 2003 Apr;15(4):422-6
references.pmid: 12622844
references.citation: Diabetes Care. 2004 Dec;27(12):2813-8
references.pmid: 15562190
references.citation: J Clin Endocrinol Metab. 2002 May;87(5):2024-32
references.pmid: 11994336
references.citation: Nature. 2002 Aug 29;418(6901):935-41
references.pmid: 12198538
references.citation: Nature. 2002 May 16;417(6886):329-35
references.pmid: 12015613
references.citation: Int J Obes Relat Metab Disord. 2004 Oct;28(10):1309-16
references.pmid: 15314624
references.citation: Clin Endocrinol (Oxf). 2001 Mar;54(3):339-46
references.pmid: 11298086
references.citation: Gen Comp Endocrinol. 1998 Nov;112(2):255-61
references.pmid: 9784309
references.citation: J Nutr. 2009 Feb;139(2):329-34
references.pmid: 19106328
references.citation: Am J Clin Nutr. 1998 Jun;67(6):1108-10
references.pmid: 9625080
references.citation: Trends Neurosci. 2013 Feb;36(2):74-82
references.pmid: 23333345
references.citation: Am J Epidemiol. 2005 Mar 15;161(6):565-74
references.pmid: 15746473
references.citation: JAMA. 2013 Apr 3;309(13):1388-96
references.pmid: 23549584
references.citation: Cardiovasc Diabetol. 2007 Jan 15;6:1
references.pmid: 17224062
references.citation: Diabetes Care. 2004 Feb;27(2):326-30
references.pmid: 14747208
references.citation: Int J Mol Sci. 2013 Mar 27;14(4):6981-7015
references.pmid: 23535335
references.citation: Ann Clin Biochem. 2001 Jan;38(Pt 1):59-60
references.pmid: 11270844
references.citation: Eur J Epidemiol. 2001;17(2):129-33
references.pmid: 11599685
references.citation: Diabetologia. 1996 Nov;39(11):1269-75
references.pmid: 8932991
references.citation: Diabetologia. 2011 Apr;54(4):749-56
references.pmid: 21188352
references.citation: Diabetes Res Clin Pract. 2010 Apr;88(1):65-70
references.pmid: 20047769
references.citation: Diabetes Care. 2011 Jun;34(6):e61-99
references.pmid: 21617108
references.citation: Eur J Pediatr. 1989 Jun;148(7):597-9
references.pmid: 2629718
references.citation: J Diabetes Sci Technol. 2009 Jul 01;3(4):668-71
references.pmid: 20144310
references.citation: N Engl J Med. 2008 Oct 9;359(15):1577-89
references.pmid: 18784090
references.citation: Med Sci Sports Exerc. 2003 Jun;35(6):1004-8
references.pmid: 12783049
references.citation: Experientia. 1993 Aug 15;49(8):654-64
references.pmid: 8395408