title: Coefficient of variation of R-R interval closely correlates with glycemic variability assessed by continuous glucose monitoring in insulin-depleted patients with type 1 diabetes.
abstract: OBJECTIVE
  In type 1 diabetic patients, insulin secretory capacity, meals and physical activity correlate with glycemic variability. Autonomic function associated with gastrointestinal motility and counterregulatory hormone secretion is another candidate which correlates with glucose variability. The aim of this study is to clarify a new clinical parameter associated with glycemic variability in insulin-depleted patients with type 1 diabetes.
  
  
  METHODS
  We studied 31 inpatients with type 1 diabetes. We evaluated glycemic variability calculated by continuous glucose monitoring, clinical parameters and the coefficient of variation of R-R interval (CVR-R). Glycemic variability was also assessed during the daytime and nighttime.
  
  
  RESULTS
  The CVR-R showed a significant negative correlation with the whole-day standard deviation (SD) (r = -0.50, p = 0.007), mean amplitude of glycemic excursions (MAGE) (r = -0.47, p=0.011), M-value (r = -0.38, p = 0.048) and mean of daily differences (MODD) (r = -0.59, p = 0.001). The CVR-R also showed a significant negative correlation with the nighttime SD (r = -0.59, p = 0.001), MAGE (r = -0.47, p=0.011), M-value (r = -0.53, p = 0.004) and MODD (r = -0.65, p = 0.0003). And furthermore, the CVR-R also showed a significant negative correlation with the daytime SD (r = -0.44, p = 0.019) and MAGE (r = -0.50, p = 0.006), but not with the daytime M-value or MODD. The nighttime SD was significantly higher in patients with diabetic polyneuropathy than in patients without it (p = 0.016), while the CVR-R was significantly lower in patients with polyneuropathy than in patients without it (p = 0.009).
  
  
  CONCLUSIONS
  CVR-R is closely correlated with glycemic variability, especially during nighttime, in insulin-depleted patients with type 1 diabetes. Measuring CVR-R may help us to presume the degree of glycemic variability in those patients.
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Iwasaki
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Kozawa
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan; Department of Community Medicine, Graduate School of Medicine, Osaka University, Suita, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukui
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Iwahashi
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan. Electronic address: aimagawa@endmet.med.osaka-u.ac.jp.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Imagawa
authors.affiliation: Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan.
authors.forename: Iichiro
authors.initials: I
authors.lastname: Shimomura
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005947:Glucose; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D005947:Glucose
keywords: Autonomic function; Coefficient of variation of R-R interval; Continuous glucose monitoring; Glycemic variability; Type 1 diabetes