Long-term treatment with EXf, a peptide analog of Exendin-4, improves β-cell function and survival in diabetic KKAy mice

► EXf is a novel peptide analog of Exendin-4 with two amino acid substitutions. ► EXf improved glycemic control and β-cell function, restored islet morphology. ► EXf stimulated proliferation and inhibited apoptosis of β-cells. ► EXf improved islet β-cell survival by PI3 K/Akt1 signal pathway. ► EXf may slow down the diabetes progress in diabetic KKAy mice.