High-protein diet is a promising strategy for diabetes treatment supporting body weight control, improving glycaemic status, cardiovascular risk factors and reducing liver fat. Here, we investigated effects of diets high in animal (AP) or plant (PP) protein on oxidative stress and antioxidant status in individuals with type 2 diabetes (T2DM). 37 obese individuals (age 64.3 ± 1.0 years) with T2DM were randomized to an isocaloric diet (30 energy(E)% protein, 30 E% fat and 40 E% carbohydrates) rich in AP or PP for 6 weeks. Markers of oxidative and nitrosative stress and antioxidant status in plasma and nitrate/nitrite levels in urine were assessed. Gene expression in subcutaneous adipose tissue (SAT) was analysed by RNA-Seq and real-time PCR. Both AP and PP diets similarly reduced plasma levels of malondialdehyde (P_AP = 0.003, P_PP = 1.6 × 10⁻⁴) and protein carbonyls (P_AP = 1.2 × 10⁻⁴, P_PP = 3.0 × 10⁻⁵) over 6 weeks. Nitrotyrosine (NT) increased upon both AP and PP diets (P_AP = 0.005, P_PP = 0.004). SAT expression of genes involved in nitric oxide (NO) and oxidative stress metabolism and urine NO metabolite (nitrate/nitrite) levels were not changed upon both diets. Plasma levels of carotenoids increased upon PP diet, whereas retinol, alpha- and gamma-tocopherol slightly decreased upon both diets. AP and PP diets similarly improve oxidative stress but increase nitrosative stress markers in individuals with T2DM. Mechanisms of the NT regulation upon high-protein diets need further investigation.

高蛋白饮食是一种有前途的糖尿病治疗策略，可支持体重控制、改善血糖状况、心血管危险因素和减少肝脏脂肪。在这里，我们研究了富含动物 (AP) 或植物 (PP) 蛋白的饮食对 2 型糖尿病 (T2DM) 患者氧化应激和抗氧化状态的影响。 37 名患有 T2DM 的肥胖个体（年龄 64.3 ± 1.0 岁）被随机分配至富含 AP 或 PP 的等热量饮食（30 能量 (E)% 蛋白质、30 E% 脂肪和 40 E% 碳水化合物），为期 6 周。评估了血浆中的氧化和亚硝化应激标记物以及抗氧化状态以及尿液中的硝酸盐/亚硝酸盐水平。通过 RNA-Seq 和实时 PCR 分析皮下脂肪组织 (SAT) 中的基因表达。 AP 和 PP 饮食在 6 年内同样降低了血浆丙二醛（P _AP = 0.003，P _PP = 1.6 × 10 ^-4 ）和蛋白质羰基化合物（P _AP = 1.2 × 10 ^-4 ，P _PP = 3.0 × 10 ^-5 ）的水平几周。 AP 和 PP 饮食中硝基酪氨酸 (NT) 均有所增加（P _AP = 0.005，P _PP = 0.004）。两种饮食中参与一氧化氮 (NO) 和氧化应激代谢的基因 SAT 表达以及尿液 NO 代谢物（硝酸盐/亚硝酸盐）水平均未发生变化。 PP 饮食中类胡萝卜素的血浆水平增加，而视黄醇、α-和γ-生育酚在两种饮食中均略有下降。 AP 和 PP 饮食同样可以改善 T2DM 患者的氧化应激，但会增加亚硝化应激标记物。 NT对高蛋白饮食的调节机制需要进一步研究。