Sitagliptin, a dipeptidyl peptidase-4 inhibitor, decreases systolic blood pressure in Japanese hypertensive patients with type 2 diabetes

Sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, is a newly developed oral hypoglycemic agent. Sitagliptin increases the level of glucagon-like polypeptide (GLP)-1 that increases insulin secretion. In addition, GLP-1 decreases salt intake and increases urinary salt excretion. Therefore, the sitagliptin treatment might lower blood pressure in hypertensive patients with type 2 diabetes. It also remains to be examined whether the reduction in blood pressure with sitagliptin treatment is related to the blood glucose improvement and the body weight decrease. To identify beneficial effects of sitagliptin treatment, we administered sitagliptin (50 mg) on alternate days to seventeen type 2 diabetes outpatients with insufficient blood glucose control (8 males and 9 females; mean age of 67.1 years). The patients were also treated with oral hypoglycemic agents and antihypertensive drugs for six months before and during the sitagliptin administration. We measured the level of hemoglobin (Hb) A1c, systolic blood pressure (SBP), and body mass index (BMI) for up to six months thereafter. Their BMIs remained unchanged. The levels of HbA1c were dropped from 6.5 ± 0.3% to 5.8 ± 0.3%, while SBP was also dropped from 130.0 ± 37.2 mmHg to 119.7 ± 9.4 mmHg. However, the degree of the decrease in HbA1c levels was not significantly correlated with that of SBP (r = 0.24). In conclusion, the present findings suggest that sitagliptin lowers SBP without reducing BMI, independent of the blood glucose reduction. The hypotensive effect is apparent with the alternate-day regimen of sitagliptin at a lower dose compared to the everyday medication.