一种新的“乳清”可控制糖尿病

生物通报道：血糖激增——餐后血糖“峰值”， 威胁着糖尿病患者的生命。糖尿病患者的血糖峰值，已被证实与心血管疾病、癌症、老年痴呆症、肾功能衰竭和视网膜损伤有关。目前，以色列特拉维夫大学（TAU）在国际糖尿病权威杂志《Diabetologia》发表的一项最新研究表明，一种新的方法可抑制这种致命的餐后血糖激增：早餐前食用乳清蛋白浓缩物，即存在于分离自乳酪的牛奶的水部分。

根据TAU的Daniela Jakubowicz教授和Wolfson医学中心糖尿病部门Julio Wainstein博士、希伯来大学的Oren Froy教授和隆德大学Bo Ahrén教授介绍，餐前食用乳清蛋白，甚至能使患者免于胰岛素治疗的需要。

Jakubowicz教授称：“值得注意的是，餐前食用乳清蛋白可降低餐后观察到的血糖峰值。它也能提高身体的胰岛素反应，使其处于类似或高于新型抗糖尿病药物所产生的范围。一直以来，高奶摄入量都与2型糖尿病和心血管疾病的较低风险有关，牛奶乳清蛋白可增加一种胃肠激素（称为胰高血糖素样肽-1，GLP-1）的生产，这种激素可促进胰岛素的分泌。反过来，这又会降低餐后的血糖上升。”

早餐前一杯乳清浓缩物
Jakubowicz教授说：“我们推测，通过餐前食用乳清蛋白刺激GLP-1生产，可提高胰岛素的分泌，并对2型糖尿病具有有益的降血糖作用。”

这项研究是在Wolfson医学中心15名控制良好的2型糖尿病患者中进行的。参与者被随机分配，接受250毫升含50mg乳清的水，或安慰剂，然后食用一顿标准高血糖指数的早餐，包括三片白面包和含糖果冻——旨在产生最大的餐后血糖峰值。

在餐前30分钟采集血样，此时已经食用了血清蛋白或安慰剂饮料。当食用早餐及餐后15、30、60、90、120、150和180分钟的时间间隔，进一步采集血液样本，评估葡萄糖的血浆浓度、完整GLP-1和胰岛素浓度。

一天中最重要的一餐？
研究人员发现，在餐后预加载乳清超过180分钟之后，葡萄糖水平下降了28%，在早期和晚期阶段始终这样。用乳清预加载，胰岛素和GLP-1反应也明显升高（分别为105%何141%），在早期的胰岛素反应中产生了96%的增加。

Jakubowicz教授说：“在2型糖尿病患者中通常不足的早期胰岛素反应，在乳清蛋白摄入组中明显高于安慰剂服用组，乳清蛋白预加载显著降低了早餐后的血糖升高。因此，乳清蛋白可以代表一种新的方法，提高2型糖尿病的降糖策略。”

根据这项研究结果，作者考虑进行长期的临床试验，来检测乳清蛋白摄入对糖尿病患者的持久益处。

（生物通：王英）

延伸阅读：一种遗传变异与Ⅱ型糖尿病相关

生物通推荐原文摘要：
Incretin, insulinotropic and glucose-lowering effects of whey protein pre-load in type 2 diabetes: a randomised clinical trial
Abstract
Aims/hypothesis
Since protein ingestion is known to stimulate the secretion of glucagon-like peptide-1 (GLP-1), we hypothesised that enhancing GLP-1 secretion to harness its insulinotropic/beta cell-stimulating activity with whey protein pre-load may have beneficial glucose-lowering effects in type 2 diabetes.

Methods
In a randomised, open-label crossover clinical trial, we studied 15 individuals with well-controlled type 2 diabetes who were not taking any medications except for sulfonylurea or metformin. These participants consumed, on two separate days, 50 g whey in 250 ml water or placebo (250 ml water) followed by a standardised high-glycaemic-index breakfast in a hospital setting. Participants were randomised using a coin flip. The primary endpoints of the study were plasma concentrations of glucose, intact GLP-1 and insulin during the 30 min following meal ingestion.

Results
In each group, 15 patients were analysed. The results showed that over the whole 180 min post-meal period, glucose levels were reduced by 28% after whey pre-load with a uniform reduction during both early and late phases. Insulin and C-peptide responses were both significantly higher (by 105% and 43%, respectively) with whey pre-load. Notably, the early insulin response was 96% higher after whey. Similarly, both total GLP-1 (tGLP-1) and intact GLP-1 (iGLP-1) levels were significantly higher (by 141% and 298%, respectively) with whey pre-load. Dipeptidyl peptidase 4 plasma activity did not display any significant difference after breakfast between the groups.

Conclusions/interpretation
In summary, consumption of whey protein shortly before a high-glycaemic-index breakfast increased the early prandial and late insulin secretion, augmented tGLP-1 and iGLP-1 responses and reduced postprandial glycaemia in type 2 diabetic patients. Whey protein may therefore represent a novel approach for enhancing glucose-lowering strategies in type 2 diabetes.