title: Long-range correlated glucose fluctuations in diabetes.
abstract: OBJECTIVE
  Our objective is to investigate diabetes-related alteration of glucose control in diurnal fluctuations in normal daily life by detrended fluctuation analysis (DFA).
  
  
  METHODS
  The fluctuations of glucose of 12 non-diabetic subjects and 15 diabetic patients were measured using a continuous glucose monitoring system (CGMS) over a period of one day. The glucose data was calculated by the DFA method, which is capable of revealing the presence of long-range correlations in time series with inherent non-stationarity.
  
  
  RESULTS
  Compared with the non-diabetic subjects, the mean glucose level and the standard deviation are significantly higher in the diabetic group. The DFA exponent alpha is calculated, and glucose time series are searched for the presence of negatively (0.5 < alpha < 1.5) or positively (1.5 < alpha) correlated fluctuations. A crossover phenomenon, i.e. a change in the level of correlations, is observed in the non-diabetic subjects at about two hours; the net effects of glucose flux/reflux causing temporal changes in glucose concentration are negatively correlated in a "long-range" (> two hours) regime. However, for diabetic patients, the DFA exponent alpha = 1.65 +/- 0.30, and in the same regime positively correlated fluctuations are observed, suggesting that the net effects of the flux and reflux persist for many hours.
  
  
  CONCLUSIONS
  Such long-range positive correlation in glucose homeostasis may reflect pathogenic mechanisms of diabetes, i.e., the lack of the tight control in blood glucose regulation. Using modern time series analysis methods such as DFA, continuous evaluation of glucose dynamics could promote better diagnoses and prognoses of diabetes and a better understanding of the fundamental mechanism of glucose dysregulation in diabetes.
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ogata
authors.forename: K
authors.initials: K
authors.lastname: Tokuyama
authors.forename: S
authors.initials: S
authors.lastname: Nagasaka
authors.forename: A
authors.initials: A
authors.lastname: Ando
authors.forename: I
authors.initials: I
authors.lastname: Kusaka
authors.forename: N
authors.initials: N
authors.lastname: Sato
authors.forename: A
authors.initials: A
authors.lastname: Goto
authors.forename: S
authors.initials: S
authors.lastname: Ishibashi
authors.forename: K
authors.initials: K
authors.lastname: Kiyono
authors.forename: Z R
authors.initials: ZR
authors.lastname: Struzik
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation*; D016022:Case-Control Studies; D003920:Diabetes Mellitus / Q000503:physiopathology*; D005260:Female; D017709:Fractals; D005947:Glucose / Q000032:analysis; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D013997:Time Factors
chemical_list: D005947:Glucose