Dipeptidyl peptidase-4 inhibitors: 3 years of experience

According to the latest American Diabetes Association guidelines, lowering glycated hemoglobin (HbA(1c)) to below or around 7% has been shown to reduce microvascular and neuropathic complications of diabetes and, if implemented soon after the diagnosis of diabetes, is associated with long-term reduction in macrovascular disease. Recently a new class of antidiabetes drugs has been developed, dipeptidyl peptidase-4 (DPP-4) inhibitors, which act by inhibiting DPP-4, the enzyme that inactivates glucagon-like peptide-1 (GLP-1). Through the inhibition of DPP-4, DPP-4 inhibitors enhance the effects of GLP-1 and glucose-dependent insulinotropic peptide, increasing glucose-mediated insulin secretion and suppressing glucagon secretion. We conducted a review analyzing clinical efficacy and safety of DPP-4 inhibitors, both alone and in combination with other antidiabetes drugs, including randomized controlled trials about sitagliptin, vildagliptin, saxagliptin, and linagliptin conducted in the latest 15 years. We concluded that, once metformin fails to maintain glycemic control, addition of DPP-4 inhibitors should be the logical choice: they seems to lower HbA(1c) levels by 0.6-0.9 percentage points and to have a comparable effect on HbA(1c) versus the addition of a sulfonylurea or glitazone. They also have positive effects on β-cell function, and they have neutral effects on body weight. Furthermore, DPP-4 inhibitors prevent the risk of hypoglycemia posed by sulfonylureas.