(P472) Association between diabetes and the vaginal microbiota

Background: Type 2 diabetes (T2D) is a known risk factor for urinary tract infection and vulvovaginal candidiasis; vaginal microbiota may modulate this infection risk. We sought to assess the associations between diabetes and the vaginal microbiota - specifically whether diabetes reduces abundance of vaginal Lactobacillus spp., which produce lactic acid and protect the urogenital tract. Data on the vaginal microbiota may contribute to improving urogenital health of those with diabetes.

Methods: This secondary analysis included 811 participants (2,301 person-visits) aged 35-60 recruited to a 2-year observational cohort with mid-vaginal swab collection every six months. Diabetes cases were defined by any of the following: serum glycated albumin (GA) levels >16.5% (HbA1c not available), self-reported diabetes medications or history. Controls included the remaining population. Vaginal microbiota was characterized by 16S rRNA gene sequencing and clustered into community state types (CSTs) by VALENCIA, a nearest centroid algorithm based on a reference dataset. Mixed-effects multinomial logistic regression models assessed the association of diabetes and CSTs, and bootstrapping methods were used to calculate confidence intervals.

Results: Among 130 person-visits from 45 participants with diabetes, 45% had L. crispatus, L. jensenii, L. gasseri-dominated (CST I/II/V), 12% had L. iners-dominated (CST III) and 43% had low-Lactobacillus (CST IV) microbiota. Cases were more likely than controls to be in postmenopause (70% vs 62%) and report African American race (32% vs 17%). Diabetes cases had significantly reduced odds of L. iners-dominated CST III (aOR: 0.54, 95% CI: 0.31-0.81) than controls (12% vs. 24%) and no association with low-Lactobacillus CST IV (aOR=01.05, 95% CI: 0.76-1.44) compared to Lactobacillus-dominated CST I/II/V in a model adjusted for menopause status and race. Point estimates were similar when only GA was assessed as a biomarker of diabetes on a subset of samples (1,001 person-visits).

Conclusion: Our findings indicate diabetes is significantly associated with reduced L. iners. It appeared those with diabetes had even frequencies of low-Lactobacillus vaginal microbiota and the more optimal Lactobacillus-dominated CSTs. L. iners is metabolically distinct from other lactobacilli, only producing L-lactic acid (not the more protective D-lactic acid), and is associated with increased STIs. Future studies may further characterize how diabetes affects the vaginal microenvironment.