避免糖尿病前期继续进展 减重最重要

费城——根据美国糖尿病教育者协会(AADE)年会上公布的美国营养与饮食学会(AND)工作组建议草案，减轻体重是预防糖尿病前期进展至2型糖尿病的主要生活方式干预措施，但其他饮食干预措施也有帮助。

除了减轻体重之外，草案也提倡注册饮食营养师为糖尿病前期患者提供药物营养治疗及制订个体化的大量营养元素分布计划。


Patricia Davidson医生(左)和Shelley Mesznik女士

起草专家组组长Patricia Davidson医生表示，注册饮食营养师和有资质的糖尿病教育者在糖尿病管理团队中负责提供药物营养治疗，他们在预防2型糖尿病发生方面发挥重要作用。最终的建议版本将于今年晚些时候发表。

建议草案也提倡降低血糖指数和血糖负荷。专家组成员Shelley Mesznik女士是纽约克斯科山的注册饮食学家和有资质的糖尿病教育者，她表示降低血糖负荷可能有益也可能无效，但没有坏处，因此可以尝试。

此外，草案提倡通过摄入植物蛋白而非动物蛋白来预防糖尿病，但称目前尚无证据表明饮食中特定脂肪类型的量会影响糖尿病进展。草案称虽然有证据支持通过体力活动(135~180分钟/周)来预防患者进展至代谢综合征，但尚无文献证实体力活动对糖尿病的发生风险有影响。

虽然两位发言者认可药物营养治疗，但她们强调应首要通过调节生活方式或减肥手术减轻体重。Mesznik女士表示，如果患者询问减轻体重的目标，我们可提出减轻10%~15%的目标，不过最重要的是让患者朝着正确的方向前进：体重真正减轻了比减轻多少更重要。

草案指出，一些边际干预措施(如降低血糖负荷和指数、使用植物蛋白及增加体力活动)只有在体重减轻的情况下才具有效力。

专家组进行文献回顾，以确定饮食是否可降低2型糖尿病发生的风险，并以文献回顾得出的总体证据作为制订建议草案的基础，但这些证据只供营养和饮食学会的成员查阅。

专家组也探讨了糖尿病高危患者的定义，并讨论了因糖尿病前期(基于空腹或激发性血糖水平或血液血红蛋白A1c水平)而具有风险的患者与因代谢综合征而具有风险的患者之间的差异。大部分讨论的干预措施在这两个人群中的效力均等，除了锻炼之外，锻炼在代谢综合征人群中的效力更高。

专家组还评论了日益增加的糖尿病前期现患率。2010年，美国疾病预防控制中心(CDC)估计7900万≥20岁美国人(包括半数的≥65岁美国人)属于糖尿病前期。2009年，CDC估计约1/3的≥20岁美国人患有代谢综合征。

Davidson医生和Mesznik女士均声明无经济利益冲突。

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By: MITCHEL L. ZOLER, Clinical Endocrinology News Digital Network

PHILADELPHIA – Weight loss is the cornerstone of lifestyle measures to prevent people with prediabetes from progressing to type 2 diabetes, but other dietary steps also help, according to draft recommendations from a working group of the Academy of Nutrition and Dietetics.

In addition to weight loss, the new recommendations call for a registered dietician nutritionist to provide medical nutrition therapy to people with prediabetes and to produce individualized plans for macronutrient distribution, Patricia Davidson, DCN, said at the annual meeting of the American Association of Diabetes Educators.
 
"A registered dietician nutritionist and certified diabetes educator who provides medical nutrition therapy as part of a diabetes management team plays an important role in preventing onset of type 2 diabetes," said Dr. Davidson, who practices in Westfield, N.J., and chaired the panel that drafted the recommendations.

The finalized, published version is planned for later this year, she said.

The draft recommendations also call for an attempt at reducing a person’s glycemic index and glycemic load. "Reducing glycemic load may or may not help, but it can’t hurt, so we try it," said Shelley Mesznik, a member of the recommendation panel and a registered dietician and certified diabetes educator in Mount Kisco, N.Y.

In addition, the recommendations call for consumption of vegetable protein rather than animal protein for prevention of diabetes, but say there is no evidence that the amount of particular fat types in the diet affects progression to diabetes. The recommendations say that while evidence supports physical activity as a means to prevent progression to metabolic syndrome (when done for 135-180 min/week), there is no documented effect of activity on development of diabetes.

Despite endorsing medical nutrition therapy, both speakers highlighted the primacy of weight loss, achieved by lifestyle modification or bariatric surgery.

"We definitely found that weight loss is the key," said Dr. Davidson.

"If a patient asks for a number, we say aim to lose 10%-15%, but we’re looking for trends in the right direction; loss is more important than the size of the loss," Ms. Mesznik said.

The recommendations specify that several of the more marginal interventions, such as reduced glycemic load and index, use of vegetable protein, and increased physical activity, have evidence for efficacy only in the context of concurrent weight loss.

The panel performed a literature review to determine whether diet can reduce the risk for development of type 2 diabetes. The evidence summaries drawn from this literature that form the bases for the recommendations are available only to members of the Academy of Nutrition and Dietetics, Dr. Davidson said.

The work group also addressed the definition of people at high risk for diabetes, and discussed the differences between patients at risk because of prediabetes – based on fasting or challenged glucose levels or blood level of hemoglobin A1c, and those at risk with metabolic syndrome. Most interventions discussed appear equally effective in both populations, except for exercise, which is more effective for metabolic syndrome.

The panel also commented on the growing prevalence of prediabetes. In 2010, the Centers for Disease Control and Prevention estimated that 79 million Americans aged 20 or older had prediabetes, which included about half of those aged 65 or older, said Ms. Mesznik. In 2009, the CDC estimated that about a third of Americans aged 20 years or older had metabolic syndrome.

Dr. Davidson and Ms. Mesznik had no disclosures.