DPP4 and diabetes mellitus: Higher serum DPP-4 activity was found in patients with chronic C-virus hepatitis, which infectious disease is well known to be associated with diabetes mellitus and insulin resistance.[8], [9] DPP-4 (identical to CD26) is detectable in soluble form in the serum and DPP-4 is widely expressed in the body including bile canaliculi, hepatocytes and hepatic stellate cells (HSCs).[10], [11]