Eating for Your Gut Bacteria May Cut Cardiometabolic Risk in Type 2 Diabetes

People with type 2 diabetes already face a convergence of metabolic problems: unstable blood sugar, disrupted lipid profiles, chronic low-grade inflammation, and elevated blood pressure, all compounding one another. A new cross-sectional study published in Scientific Reports by Chambari M et al. now adds a promising piece to that puzzle, suggesting that eating patterns designed to support gut microbiota are associated with meaningfully lower overall cardiometabolic dysregulation in this population. The findings are preliminary, but the signal is consistent enough to deserve a closer look.

DI-GM Score and Reduced Cardiometabolic Dysregulation in T2D

The study used a relatively new tool called the Dietary Index for Gut Microbiota, or DI-GM, which was developed by Kase et al. in 2024 after a synthesis of 106 prior studies. The index scores 14 dietary components on a scale from 0 to 14: 10 foods or nutrients considered beneficial for gut microbiota, including fermented dairy, chickpeas, whole grains, fiber, avocados, broccoli, coffee, and green tea, and 4 considered unfavorable, including red meat, processed meat, refined grains, and a high-fat diet defined as obtaining 40% or more of daily energy from fat. Each component is scored 0 or 1 based on whether a person's intake meets a sex-specific median threshold.

Among 385 adults with type 2 diabetes recruited from diabetes clinics in Zanjan, Iran, participants in the highest DI-GM quartile showed significantly lower cardiometabolic dysregulation scores than those in the lowest quartile (β = -0.31; 95% CI: -0.42, -0.20; P-trend < 0.001). Each one-standard-deviation increase in DI-GM score was associated with a -0.17 reduction in the composite dysregulation score (95% CI: -0.24, -0.10). These associations held up after adjustment for demographic, lifestyle, and clinical covariates, and restricted cubic spline analysis found the dose-response relationship to be linear, with no evidence of a threshold or plateau effect.

Why This Matters for the 500 Million People Living With Diabetes

Cardiometabolic dysregulation is not a single problem in type 2 diabetes; it is a web of interconnected failures spanning glucose handling, lipid metabolism, liver enzyme activity, and vascular inflammation. Gut microbiota composition and cardiometabolic disorders have been linked in a growing body of research, and changes to the gut microbiome have been tied to increased type 2 diabetes risk in prospective work from Harvard Medical School. Meanwhile, cardiometabolic diseases affect roughly 11% of US adults with diagnosed diabetes and carry substantial morbidity and mortality, according to CDC surveillance data. If dietary patterns that promote a healthier microbiome can simultaneously blunt multiple dysregulation pathways, that would be a meaningful practical lever, one requiring no prescription and no procedure.

The composite dysregulation score used in this study captured glycemic control, lipid profile, inflammation markers, liver enzymes, and blood pressure together, making it a broader measure than a single biomarker like HbA1c. That breadth is part of what makes the inverse association with DI-GM scores worth taking seriously, even at this early stage.

How the Study Assessed Diet and Metabolic Health

Dietary intake was captured using a validated 168-item food frequency questionnaire, and DI-GM scores were derived from those responses according to the published scoring protocol. The composite cardiometabolic dysregulation score was built from standardized clinical markers. Multivariable linear regression estimated associations across DI-GM quartiles and per standard-deviation increment, while restricted cubic splines tested for non-linearity in the dose-response relationship. The DI-GM tool itself has been validated in NHANES data, where higher scores correlated with elevated urinary enterodiol and enterolactone, two biomarkers reflecting gut microbiota diversity, lending some biological plausibility to the current findings.

Biologically, the pathway connecting a microbiota-supportive diet to lower cardiometabolic dysregulation likely runs through several mechanisms: fermentation of dietary fiber producing short-chain fatty acids that reduce systemic inflammation, modulation of bile acid metabolism affecting lipid profiles, and gut-barrier integrity influencing insulin sensitivity. Foods like whole grains, legumes, and fermented dairy that score well on the DI-GM have all been individually associated with favorable metabolic outcomes in high-fiber and Mediterranean dietary patterns studied in T2DM populations.

Limits of a Cross-Sectional Design

The most important caveat here is architectural: this is a cross-sectional study. Participants were assessed at a single point in time, which means the data can describe an association but cannot establish whether better diet preceded better metabolic health, or whether healthier individuals simply eat differently. Reverse causation and unmeasured confounding cannot be ruled out.

The study also did not directly measure the gut microbiome. The DI-GM is a dietary proxy for microbiota health, validated against urinary biomarkers, but it is not a substitute for quantitative microbiome profiling, which would be needed to confirm that the dietary pattern is actually shifting microbial composition in the expected direction. As noted in a recent systematic review, many gut microbiota intervention studies are limited by short duration and heterogeneity in microbiome analysis methods, and observational work faces its own version of that problem.

The sample, while reasonably sized at 385 participants, was drawn from a single city in Iran, which limits how readily the findings generalize to other ethnic groups and healthcare contexts.

What Prospective Studies Need to Test Next

Confirming this association will require longitudinal work that follows people with type 2 diabetes over time, ideally pairing dietary assessment with direct gut microbiome sequencing and repeated metabolic measurements. Intervention trials that deliberately shift DI-GM scores and then track cardiometabolic outcomes would be more convincing still. Researchers have flagged dietary fibers and prebiotics as promising low-risk strategies for gut microbiota modulation in T2DM, and the DI-GM framework could provide a practical scoring tool for stratifying participants in such trials.

For now, the Zanjan cohort study by Chambari M et al. adds to a coherent, if still circumstantial, picture: dietary patterns that favor whole grains, legumes, fermented dairy, and fiber-rich vegetables while limiting red meat, processed meat, and refined grains are associated with lower multisystem cardiometabolic dysregulation in adults already managing type 2 diabetes. That is not a prescription, but it is a direction worth following with more rigorous study designs.

Evidence rating

EMERGING — 80/100

Caveats:

• Cross-sectional design: this study shows an association only and cannot establish whether diet causes changes in cardiometabolic health or vice versa.
• Single-centre Iranian cohort (n=385); findings may not generalise to other populations or healthcare settings.
• No direct gut microbiome measurements were taken — the dietary index is a proxy for microbiota-supportive eating patterns, not a confirmed readout of microbiome composition or function.
• Dietary intake was self-reported via food frequency questionnaire, which is subject to recall and social-desirability bias.
• Funding source was not disclosed; independent replication has not yet been conducted for this specific study.

Cross-sectional study of 385 adults with type 2 diabetes (Zanjan, Iran). Reports an inverse association between a validated 14-component Dietary Index for Gut Microbiota and a composite cardiometabolic dysregulation score, with a linear dose-response relationship. The design establishes association only, not causality or temporality, and no direct gut microbiome measurements were obtained. The DI-GM tool itself is newly developed (2024) and independent replication of these specific findings has not yet been reported.

References

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3. Changes to Gut Microbiome May Increase Type 2 Diabetes Risk | Harvard Medical School. hms.harvard.edu. https://hms.harvard.edu/news/changes-gut-microbiome-may-increase-type-2-diabetes-risk
4. Alain K. Koyama, Kai McKeever Bullard, Fang Xu, et al. (2024). Prevalence of Cardiometabolic Diseases Among Racial and Ethnic Subgroups in Adults — Behavioral Risk Factor Surveillance System, United States, 2013–2021. MMWR. Morbidity and Mortality Weekly Report. https://doi.org/10.15585/mmwr.mm7303a1
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8. Dietary Fibers and Prebiotics for Gut Microbiota Modulation in Type 2 Diabetes: Mechanisms and Therapeutic Potential. mdpi.com. https://www.mdpi.com/2072-6643/18/3/930