Metabolic Diseases Significantly Alter Oral Bacteria

Dentistry Today


Metabolic diseases—characterized by high blood pressure, high blood sugar, and obesity—increase salivary glucose, alter oral bacteria, and increase the risk of cavities and gum disease, reinforcing the need for preventive dental care and greater integration between medical and dental care, according to the Forsyth Institute and the Dasman Diabetes Institute in Kuwait.

“The mouth represents a rich microbiome that is easily accessible,” said J. Max Goodson, DDS, PhD, the study’s lead author and senior member of the staff at the Forsyth Institute Department of Applied Oral Sciences. “Our research is providing further evidence of the connections between the mouth and some of society’s most costly and deadly systemic diseases and of the importance of using the mouth as a tool for preventive health.”

The study measured the glucose concentration, bacterial counts, and relative frequencies of 42 bacterial species in whole saliva samples from 8,173 Kuwaiti adolescents with a mean age of 10 years ±0.67 years using DNA probe analysis. It also collected clinical data related to obesity, dental caries, and gingivitis.

By comparing data between adolescents with high salivary glucose (HSG) and low salivary glucose (LSG), the researchers found an association between HSG and dental caries and gingivitis. The overall salivary bacterial load in saliva decreased with increasing salivary glucose concentration.

Under HSG conditions, the bacteria count for 35 of the 42 species was significantly reduced, and relative bacterial frequencies in 27 species were altered, compared to LSG conditions. These alterations were stronger predictors of high salivary glucose than measures of oral disease, obesity, sleep, or fitness, indicating that metabolic diseases like diabetes that elevate glucose in blood and saliva can significantly alter the oral microflora.

Samples were obtained through the Forsyth Kuwait Healthy Life Study, a 5-year longitudinal cohort investigation of more than 8,000 children examining their body weight, height, blood pressure, fitness, oral disease, nutrition, sleep, saliva, and other medical history.

The study, “The Salivary Microbiome Is Altered in the Presence of High Salivary Glucose,” was published by PLOS ONE.

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