DPP-4 inhibitors in the treatment of type 2 diabetes

Although being a primary objective in the management of type 2 diabetes, optimal glycaemic control is difficult to achieve and usually not maintained over time. Type 2 diabetes is a complex pathology, comprising altered insulin sensitivity and impaired insulin secretion. Recent advances in the understanding of the physiological functions of incretins and their degrading enzyme dipeptidyl-peptidase (DPP)-4 have led to the 'discovery' of a new class of oral anti-diabetic drugs. Several DPP-4 inhibitors (or gliptins) with different chemical structures are now available. These agents inhibit the degradation of the incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and hence potentiate glucose-dependent insulin secretion. DPP-4 inhibitors inhibit DPP-4 activity by almost 100% in vitro, maintaining a ≥ 80% inhibition throughout the treatment period in vivo, thus prolonging GLP-1 half-life, and significantly reducing HbA1c generally by -0.7 to 0.8% as well as fasting and post-prandial glycaemia. They are well-tolerated with no weight gain and few adverse effects, and, of particular interest, no increase in hypoglycaemic episodes. Although different by their chemical structure and pharmacokinetic properties, the DPP4 inhibitors currently available have proven similar glucose lowering efficacy.