Analysis of the Gut Mycobiome in Adult Patients with Type 1 and Type 2 Diabetes Using Next-Generation Sequencing (NGS) with Increased Sensitivity-Pilot Study Original paper

What was studied?

This pilot study investigated gut-mycobiome-in-diabetes by profiling stool fungal communities in adults with type 1 diabetes (T1D), type 2 diabetes (T2D), and healthy controls using next-generation sequencing of the full fungal ITS region with a nested PCR approach to improve sensitivity. The authors focused on taxonomic differences (primarily phylum and genus levels) and on associations between fungal abundance and clinical metabolic markers, particularly lipid parameters and glycemic control.

Who was studied?

Seventy-six adults aged 20–65 years were included: 26 with T1D, 24 with T2D, and 26 healthy controls. Participants with diabetes were hospitalized for decompensated diabetes (2012–2015, Krakow, Poland). Key exclusions limited confounding from recent antibiotics/antimycotics or probiotics/prebiotics, immune deficiency, active GI disease (e.g., IBD, celiac), cancer, pregnancy, and other major comorbidities. Clinical characterization highlighted expected group differences: the T2D group was older with higher BMI and lower HDL-C than T1D and controls, which matters when interpreting microbiome associations.

Most important findings

Across all groups, Basidiomycota dominated at the phylum level, and Malassezia dominated at the genus level without significant between-group differences in its overall relative abundance. A key discriminatory signal was lower Ascomycota in T1D vs T2D (adjusted p≈0.033). At the genus level, the standout shift relevant to a signatures database was a marked depletion of Saccharomyces in T1D compared with both controls and T2D (Control 11.42% vs T1D 0.58%; T1D 0.58% vs T2D 9.35%; both highly significant). Additional genus-level differences included lower Naganishia and Bullera in T2D, higher Tilletiopsis and Vishniacozyma in T2D, and higher Udeniomyces in T1D. Clinically anchored correlations suggested metabolic links: in T1D, Saccharomyces correlated positively with total cholesterol and LDL-C; in T2D, Malassezia correlated negatively with total cholesterol, and Penicillium correlated negatively with BMI. Species-level Malassezia signals (reported as exploratory) included M. globosa positively correlating with HbA1c in T1D and M. restricta negatively correlating with LDL-C and total cholesterol in T2D.

Key implications

For clinicians, the practical message is that fungal community structure (the gut mycobiome) may carry metabolic signal that is distinct from bacterial profiles and potentially stratifies diabetes phenotypes—here, most clearly via Saccharomyces depletion in T1D and lipid-linked Malassezia associations in T2D. However, this is a small, cross-sectional pilot with notable group differences in age/BMI and without granular diet/medication data, so these findings are best treated as hypothesis-generating signatures rather than actionable targets. For a microbiome signatures database, the strongest extractable entries are genus-level shifts (Saccharomyces, Naganishia, Udeniomyces, Tilletiopsis) plus the directionality of lipid correlations (Saccharomyces↔LDL in T1D; Malassezia↔cholesterol in T2D), with species-level Malassezia signals flagged as exploratory due to classification limits and analytic choices.

Citation

Salamon D, Sroka-Oleksiak A, Gurgul A, Arent Z, Szopa M, Bulanda M, Małecki MT, Gosiewski T. Analysis of the Gut Mycobiome in Adult Patients with Type 1 and Type 2 Diabetes Using Next-Generation Sequencing (NGS) with Increased Sensitivity—Pilot Study. Nutrients. 2021;13(4):1066. doi:10.3390/nu13041066