SYNBIOTIC SUPPLEMENTATION IN TYPE 2 DIABETES: METABOLIC AND INFLAMMATORY OUTCOMES AND GUT MICROBIOTA

Type 2 diabetes mellitus (T2DM) is associated with metabolic disturbances, chronic low-grade inflammation, and changes in the gut microbiota. This study evaluated the effects of synbiotic supplementation on metabolic and inflammatory parameters and selected gut bacterial targets in individuals with T2DM. A 60-day randomized, placebo-controlled trial was conducted with 40 participants, of whom 28 completed the study (synbiotic, n = 20; placebo, n = 8). The synbiotic formulation provided 5 × 10⁹ CFU/day of Bifidobacterium adolescentis, Bifidobacterium breve, Lactobacillus paracasei, Lactobacillus plantarum, and Lactobacillus rhamnosus, together with 2.0 g of inulin and 1.7 g of fructooligosaccharides. Glycemic, lipid, and inflammatory markers were assessed at baseline and after 60 days. Selected bacterial targets were analyzed by species-specific SYBR Green qPCR using a qualitative presence/absence approach. Between-group analyses were complemented by ANCOVA adjusted for baseline values and age. The study was approved by the Research Ethics Committee (CAAE 86537424.6.0000.5368). Within the synbiotic group, significant metabolic changes were observed after 60 days, with reductions in fasting glucose, triglycerides, and total cholesterol. Total cholesterol also remained significantly lower in the adjusted between-group analysis, with a day-60 difference of −19.8 mg/dL in the synbiotic group compared with placebo (95% CI, −35.2 to −4.4; p = 0.014). The change in insulin differed between groups in the unadjusted analysis (p = 0.049), but this difference was no longer significant after adjustment. No consistent differences were observed for HbA1c, HOMA-IR, body weight, or body mass index, while TNF-α and IL-6 were not significantly affected by the intervention. qPCR detection patterns showed marked interindividual variability, and some of the supplemented species were detected less frequently at the end of the intervention, without statistically significant differences. This pattern may reflect the dynamic adaptation of the gut microbiota during supplementation, including transient colonization and competition with resident microorganisms, although these mechanisms cannot be confirmed by the qualitative approach used. Overall, synbiotic supplementation was associated with favorable within-group metabolic changes, particularly in the lipid profile, while total cholesterol also showed a significant adjusted between-group difference. Larger studies using quantitative microbiota methods are needed to confirm these findings.

Funding: FAPESC and CAPES.