title: The salivary microbiome is altered in the presence of a high salivary glucose concentration.
abstract: BACKGROUND
  Type II diabetes (T2D) has been associated with changes in oral bacterial diversity and frequency. It is not known whether these changes are part of the etiology of T2D, or one of its effects.
  
  
  METHODS
  We measured the glucose concentration, bacterial counts, and relative frequencies of 42 bacterial species in whole saliva samples from 8,173 Kuwaiti adolescents (mean age 10.00 ± 0.67 years) using DNA probe analysis. In addition, clinical data related to obesity, dental caries, and gingivitis were collected. Data were compared between adolescents with high salivary glucose (HSG; glucose concentration ≥ 1.0 mg/d, n = 175) and those with low salivary glucose (LSG, glucose concentration < 0.1 mg/dL n = 2,537).
  
  
  RESULTS
  HSG was associated with dental caries and gingivitis in the study population. The overall salivary bacterial load in saliva decreased with increasing salivary glucose concentration. Under HSG conditions, the bacterial count for 35 (83%) of 42 species was significantly reduced, and relative bacterial frequencies in 27 species (64%) were altered, as compared with LSG conditions. These alterations were stronger predictors of high salivary glucose than measures of oral disease, obesity, sleep or fitness.
  
  
  CONCLUSIONS
  HSG was associated with a reduction in overall bacterial load and alterations to many relative bacterial frequencies in saliva when compared with LSG in samples from adolescents. We propose that hyperglycemia due to obesity and/or T2D results in HSG and subsequent acidification of the oral environment, leading to a generalized perturbation in the oral microbiome. This suggests a basis for the observation that hyperglycemia is associated with an increased risk of dental erosion, dental caries, and gingivitis. We conclude that HSG in adolescents may be predicted from salivary microbial diversity or frequency, and that the changes in the oral microbial composition seen in adolescents with developing metabolic disease may the consequence of hyperglycemia.
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: J Max
authors.identifier: http://orcid.org/0000-0003-4225-9160
authors.initials: JM
authors.lastname: Goodson
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Mor-Li
authors.initials: ML
authors.lastname: Hartman
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Ping
authors.initials: P
authors.lastname: Shi
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Hatice
authors.initials: H
authors.lastname: Hasturk
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Tina
authors.initials: T
authors.lastname: Yaskell
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Jorel
authors.initials: J
authors.lastname: Vargas
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Song
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Maryann
authors.initials: M
authors.lastname: Cugini
authors.affiliation: The Dasman Diabetes Institute, Kuwait City, Kuwait.
authors.forename: Roula
authors.initials: R
authors.lastname: Barake
authors.affiliation: The Dasman Diabetes Institute, Kuwait City, Kuwait.
authors.forename: Osama
authors.initials: O
authors.lastname: Alsmadi
authors.affiliation: Ministry of Health, Kuwait City, Kuwait.
authors.forename: Sabiha
authors.initials: S
authors.lastname: Al-Mutawa
authors.affiliation: Ministry of Health, Kuwait City, Kuwait.
authors.forename: Jitendra
authors.initials: J
authors.lastname: Ariga
authors.affiliation: Department of Applied Oral Sciences, the Forsyth Research Institute, Cambridge, Massachusetts, United States of America.
authors.forename: Pramod
authors.initials: P
authors.lastname: Soparkar
authors.affiliation: Kuwait University, Faculty of Dentistry, Kuwait City, Kuwait.
authors.forename: Jawad
authors.initials: J
authors.lastname: Behbehani
authors.affiliation: The Dasman Diabetes Institute, Kuwait City, Kuwait.
authors.forename: Kazem
authors.initials: K
authors.lastname: Behbehani
mesh_terms: D000293:Adolescent; D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification; D002648:Child; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000382:microbiology; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D064307:Microbiota; D012463:Saliva / Q000378:metabolism / Q000382:microbiology
chemical_list: D005947:Glucose