Hypoglycemic effect and the post‐treatment benefits of carrot pulp fermented by Lactobacillus casei NCU215 in type 2 diabetic mice: insights from gut microbiota regulation and restoration of pancreatic islet function

Abstract Background Type 2 diabetes mellitus (T2DM) is a chronic disease which needs strict lifestyle and medicine administration. Previous reports demonstrated that fermented carrot had an antidiabetic effect but no studies have explored the post‐treatment benefits after drug intervention. Results This study evaluated the hypoglycemic efficacy of carrot pulp fermented by Lactobacillus casei NCU215 with 4 weeks of gavage first for T2DM mice, and the post‐treatment benefits by stopping the gavage for 1 week with preliminary exploration of the mechanism. The results showed that fermented carrot pulp significantly decreased the levels of fasting blood glucose, area under the blood glucose curve, fasting serum insulin, homeostasis model assessment of insulin resistance, total cholesterol, low‐density lipoprotein cholesterol and malondialdehyde and they remained low after 1 week of withdrawal of the intervention. Western blotting proved that fermented carrot pulp protected pancreatic islets by increasing the expression of Bcl2 and inhibiting the expression of Bax, caspase‐3 and NF‐ κ B. After 1 week of withdrawal the expressions of Bcl2, Bax, caspase‐3 and NF‐ κ B remained the same trend as before. The gut microbiota analysis indicated that the increase of Faecalibaculum , Dubosiella and Bifidobacterium contributed to the antidiabetic and post‐treatment benefits. Conclusion The hypoglycemic efficacy and the post‐treatment benefits of fermented carrot pulp were elucidated with gut microbiota regulation and restoration of pancreatic islet function. The carrot pulp fermented by Lactobacillus casei NCU21 5 may provide an effective and stable treatment for T2DM. © 2025 Society of Chemical Industry.