Incretin-based drugs for type 2 diabetes: Focus on East Asian perspectives

Type 2 diabetes in East Asians is characterized primarily by β-cell dysfunction, and with less adiposity and less insulin resistance compared with that in Caucasians. Such pathophysiological differences can determine the appropriate therapeutics for the disease. Incretins, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1, are secreted in response to meal ingestion, and enhance insulin secretion glucose-dependently. Incretin-based drugs, dipeptidyl peptidase-4 inhibitors (DPP-4i) and glucagon-like peptide-1 receptor agonists, that ameliorate β-cell dysfunction with limited hypoglycemia risk are now widely used in type 2 diabetes management. Recent meta-analyses of clinical trials on DPP-4i and glucagon-like peptide-1 receptor agonists found that the drugs were more effective in Asians, most likely because of amelioration of β-cell dysfunction. In addition, we found increased glycated hemoglobin-lowering effects of DPP-4i to be associated with intake of fish in type 2 diabetes, which suggests that dietary customs of East Asians might also underlie the greater efficacy of DPP-4i. Despite the limited risk, cases of severe hypoglycemia were reported for DPP-4i/sulfonylureas combinations. Importantly, hypoglycemia was more frequent in patients also receiving glibenclamide or glimepiride, which activate exchange protein directly activated by cyclic adenosine monophosphate 2, a critical mediator of incretin signaling, and was less frequent in patients receiving gliclazide, which does not activate exchange protein directly activated by cyclic adenosine monophosphate 2. Prevention of insulin-associated hypoglycemia by DPP-4i has gained attention with regard to the enhancement of hypoglycemia-induced glucagon secretion by insulinotropic polypeptide, but remains to be investigated in East Asians. Despite the safety issues, which are paramount and must be carefully monitored, the incretin-based drugs could have potential as a first choice therapy in East Asian type 2 diabetes patients.