Dietary inorganic nitrate/nitrite supplementation reduces central and peripheral blood pressure in patients with type 2 diabetes mellitus.

BACKGROUND: Patients with type 2 diabetes mellitus (T2DM) have increased cardiovascular risk partially due to elevated blood pressure (BP). As low levels of nitric oxide (NO) may contribute to increased BP, we studied the effects of increasing NO bioavailability via 8wks of supplementation with beetroot juice containing inorganic nitrate/nitrite (4.03mmol nitrate, 0.29mmol nitrite, n=19) on central and peripheral BP relative to nitrate/nitrite-depleted beetroot juice (n=18).

METHODS: Peripheral BP was measured via an indwelling brachial arterial catheter maintained at heart-level with central BP, as well as augmentation index (AIx), measured using applanation tonometry while subjects were supine.

RESULTS: Plasma nitrate and nitrite increased following inorganic nitrate/nitrite (both p<0.05), but not placebo (p=0.63 and 0.57) supplementation. Nitrate/nitrite supplementation reduced peripheral systolic BP (148±16 to 142±18mmHg, p<0.05) but not placebo (150±19 to 149±17mmHg, p=0.93); however, diastolic BP and pulse pressure were unaffected (supplement-by-time p=0.08 and 0.22). Central systolic BP (131±16 to 127±17mmHg) and augmented pressure (13.3±6.6 to 11.6±6.9mmHg, both p<0.05) were reduced after nitrate/nitrite, but not placebo (134±17 to 135±16mmHg, p=0.62; 14.1±6.6 to 15.2±7.4mmHg, p=0.20); neither central diastolic BP nor pulse pressure changed during the interventions (supplement-by-time p=0.16 and 0.39). Inorganic nitrate/nitrite reduced both AIx (24.3±9.9 to 21.0±9.6%) and AIx normalized to a heart rate of 75bpm (21.9±10.8 to 18.5±10.6%, both p<0.05) whereas no changes were observed following placebo (24.6±9.3 to 25.6±9.9%, p=0.46; 23.0±7.0 to 24.1±9.2%, p=0.51).

CONCLUSIONS: Our data indicate inorganic nitrate/nitrite supplementation improves peripheral and central BP as well as AIx in patients with T2DM.