Oral microbiome alterations in individuals with type 1 diabetes: a systematic review.

In 30 seconds

This systematic review evaluated associations between glycemic control and oral microbial findings in people with type 1 diabetes (T1DM), distinguishing targeted tests from comprehensive microbiome profiling. Forty-two human studies were included; most were cross-sectional and used HbA1c, with varied thresholds. Targeted studies commonly linked poorer glycemic control with selected periodontal pathogens or oral Candida carriage, while findings for cariogenic microorganisms were inconsistent. Only four studies used comprehensive community profiling, and their heterogeneous results did not establish a consistent direction of diversity change. Overall, the evidence supports associations with selected microbial alterations, not causality or a uniform whole-community pattern.

Key findings

• The review included 42 studies, most of which were cross-sectional and assessed glycemic control using HbA1c.
• Targeted studies commonly associated poorer glycemic control with selected periodontal pathogens or oral Candida carriage.
• Findings for cariogenic microorganisms were inconsistent.
• Only four studies used comprehensive community profiling; methodological heterogeneity prevented a uniform conclusion about diversity change.

Why it matters

The findings suggest that poorer glycemic control may coexist with selected oral microbial alterations in T1DM, but they do not establish that glycemia causes these changes or define whole-community dysbiosis. This distinction matters when interpreting oral findings in diabetes care: current evidence supports attention to established preventive dental care and periodontal assessment, not microbiome-based risk classification.

What to keep in mind

Most included studies were cross-sectional, and methods and HbA1c thresholds varied substantially. Only four studies used comprehensive community profiling, limiting conclusions about whole-community changes and causality.