Ketogenic diet alleviates β-cell dedifferentiation but aggravates hepatic lipid accumulation in db/db mice

•The ketogenic diet significantly reduced fasting blood glucose and insulin levels and improved glucose tolerance in db/db mice.•The ketogenic diet played a role in glucose metabolism by upregulating β-cell–specific transcription factors and reversing β-cell dedifferentiation.•However, the ketogenic diet induced hepatic lipid accumulation and aggravated the inflammatory response in the liver of db/db mice.