Glycaemic Status in T2DM Patients Influences Periodontal Microbiome and Metabolome

Objectives: There is growing evidence of a bidirectional link between periodontitis and type 2 diabetes mellitus (T2DM). But few studies have focused on the specific effects of glycaemic status on periodontitis-related microbes and metabolism. This study evaluated if periodontal microbiome and metabolome of T2DM patients is affected by glycaemic status.
Methods: Saliva and gingival crevicular fluid (GCF) samples were collected from T2DM patients with periodontitis. The patients were allocated into three groups according to systemic glycaemic status: good control (GC, HbA1c<6.5%, n=13), medium control (MC, 6.5%≤HbA1c≤7.0%, n=15), poor control (PC, HbA1c>7.0%, n=14). MC group and PC group can be refered to as IC (inadequete control) group. The microbiome was evaluated using full-length 16S rRNA gene sequencing, and the metabolome was accessed using gas chromatography-mass spectrometry.
Results: When HbA1c was well controlled, the microbial structure and function of saliva and GCF were similar. When HbA1c was not well controlled, the flora in GCF showed higher α-diversity(P<0.05), and a more pronounced trend toward separation with the flora in saliva by β-diversity. And there were 6 functional pathways including linoleic acid metabolism that were significantly different(P<0.05). For GC group and IC group, there were 7 different microorganisms including Veillonella atypica(P<0.05), and 19 different metabolites including glutamic acid, nicotinamide and lactic acid(|log2(FC)|>1) in saliva between the two groups, of which 16 metabolites were significantly increased in IC group, and 3 metabolites were significantly decreased.
Conclusions: Glycaemic status in T2DM patients has an impact on periodontal microbiome and metabolome. When blood glucose control is inadequate, different niches such as saliva and GCF show different changing trends.