Effects of Cinnamaldehyde on the Gut Microbiota Composition in Patients with Type 1 Diabetes Mellitus

Objective To investigate the effects of cinnamaldehyde on the gut microbiota composition in patients with type 1 diabetes mellitus (T1DM). [Methods] A total of 20 T1DM patients meeting inclusion/exclusion criteria were enrolled in a randomized, double-blind, parallel-group controlled clinical trial. Patients were randomly assigned to two groups: the cinnamaldehyde group received 120 mg/day of cinnamaldehyde after breakfast alongside their existing medication regimen, while the control group continued standard treatment without cinnamaldehyde supplementation. The intervention lasted 42 days. Clinical data including fasting blood glucose levels were monitored, and fecal samples were collected via mid-stream swab sampling at both baseline and post-intervention stages for metagenomic sequencing analysis of gut microbiota. [Results] In the cinnamaldehyde group, reductions in HbA1c and blood glucose coincided with decreases in triglycerides, HDL-C, ALT, AST, and serum creatinine levels. Conversely, these parameters increased in the control group, with statistically significant elevations observed in total cholesterol and ALT (P < 0.05). These findings suggest that cinnamaldehyde adjunct therapy effectively enhances glycemic control while mitigating drug-related adverse effects. [Conclusion] Cinnamaldehyde administration promoted enrichment of probiotic bacteria including Akkermansia, Bifidobacterium adolescentis, and Faecalibacterium prausnitzii. It modulated the abundance of functional microbial taxa critical for metabolic disorders, thereby improving host glucose and lipid metabolism. Daily cinnamaldehyde supplementation combined with insulin therapy significantly improved glycemic control, reduced medication side effects, enhanced gut microbiome diversity, and optimized the intestinal microecological environment in T1DM patients.