Enhancing Carbohydrate Quality in Diabetes Management

由于糖尿病并发症的程度与糖尿病控制水平直接相关，目前的糖尿病治疗方案强调通过使用强化胰岛素治疗方案和碳水化合物计数来维持接近正常的血糖。虽然建议适度使用单糖，但碳水化合物的来源或质量目前并未被认为是该方案的组成部分。然而，越来越多的证据表明，具有较低血糖指数的碳水化合物可以减少餐后高血糖并改善整体血糖控制。按照美国卫生和农业部2005年《美国人膳食指南》，这种饮食将包括从营养丰富的天然食品中摄入更多的碳水化合物——全谷物、水果、蔬菜和豆类。与此同时，患有1型糖尿病的儿童的饮食中水果、蔬菜和全谷物含量低，饱和脂肪含量高。由于血脂异常和心血管疾病的风险增加，以及最近在青年糖尿病患者中观察到的心血管危险因素的高患病率，这种不良的饮食质量尤其令人担忧。

Because degree of diabetes complications is directly linked to level of diabetes control, current diabetes regimens emphasize maintenance of near-normal glycemia through the use of intensive insulin regimens and carbohydrate counting. While moderation in the use of simple sugar is recommended, the source or quality of carbohydrate is not currently considered an integral part of the regimen. However, a growing body of evidence indicates that carbohydrates with a lower glycemic index may reduce postprandial hyperglycemia and improve overall glycemic control. Such a diet would consist of greater consumption of carbohydrate from nutrient-dense whole foods - whole grains, fruits, vegetables, and legumes - in accordance with the HHS-USDA 2005 Dietary Guidelines for Americans. Concurrently, children with type 1 diabetes are consuming diets low in fruits, vegetables, and whole grains, and high in saturated fat. This poor diet quality is particularly concerning due to the increased risk of dyslipidemia and cardiovascular disease and high the high prevalence of cardiovascular risk factors recently observed in youth with diabetes. Two pilot studies have provided data to guide the development of this program of research. A pilot study was conducted during the summer of 2004 to investigate the feasibility and acceptability of implementing a low glycemic index diet in the diabetes camp setting. Camp provides an ideal setting to introduce youth to a lower glycemic index diet, because exposure to foods is controlled, and a sufficient number of meals are served to assess acceptability across a range of foods. Youth ages 7 to 15 attending a diabetes summer camp were served standard diabetes camp menus and lower glycemic index diabetes camp menus in a daily alternating cross-over design. Measures of satisfaction with the camp meals and snacks were obtained from youth and staff, and observations of meal consumption were conducted. Additional data were collected via focus groups, and self-report of food patterns and preferences. Meal plans and blood glucose monitoring data were obtained from camp records. A pilot study was conducted during the summer of 2006 testing blood glucose response to low and high glycemic index meals in youth with diabetes using continuous blood glucose monitoring. In this study, youth with diabetes participated in 5 days of continuous blood glucose monitoring during which they received both low and high glycemic index meals both in a structured clinic setting and in the home environment. Food intake, insulin, and blood glucose self-monitoring were recorded. Analyses are in progress, and include comparison of mean blood glucose, excursions, and variability. A series of focus groups addressed perceptions of healthful eating among families of children with type 1 diabetes to guide development of a behavioral intervention to be testing in the upcoming efficacy trial. The focus groups were conducted separately with children, adolescents, and parents. In addition, a cross-sectional observational study assessing potential modifiable factors associated with dietary intake was conducted. Data collected include child and parent dietary intake, family eating patterns, food availability, nutrition knowledge, parent and child beliefs regarding healthful eating (e.g., barriers, outcome expectations, self-efficacy), and parent and peer modeling of healthful eating. An efficacy trial of a behavioral intervention designed to increase consumption of carbohydrates from lower glycemic, nutrient dense, whole food sources is underway. The purpose of this trial is to determine the efficacy of a behavioral nutrition intervention for children with type 1 diabetes ages 8 to 16 and their families. The goal of the intervention is to increase the consumption of carbohydrates from low glycemic index, nutrient-dense whole foods (i.e., fruits, vegetables, whole grains, legumes). The effect of the dietary intervention on glycemic control and other diabetes-specific outcomes (e.g., glycemic excursions, insulin dose and frequency of hypoglycemia), body composition, lipid profiles, oxidative stress and inflammation will be determined. In addition, effects of the intervention on psychosocial factors (e.g., quality of life and disordered eating behaviors) will be investigated. Families were randomized to either a behavioral nutrition intervention or a control condition. Participants in both groups use episodic masked continuous glucose monitoring (CGM) at predetermined intervals during the study. Participants in the control condition receive usual diabetes care, including general diabetes-related education promoting a healthy lifestyle. Participants in the behavioral nutrition intervention participate in a series of family-based sessions during the first 12 months of the study. These sessions will use behavioral techniques and educational content to promote increased consumption of carbohydrates from low glycemic index, nutrient-dense whole foods, and decreased consumption of highly processed carbohydrate-containing foods. Additional booster contacts occur for the following 6 months of the study. Dietary intake, social and cognitive mediators, and health outcomes are assessed at baseline, 6 months, 12 months, and 18 months. Primary outcomes are dietary quality and hemoglobin A1c, an established measure of glycemic control. It is anticipated that this research will provide data that are critical for guiding dietary guidelines for persons with diabetes. Findings will advance understanding of: 1) the efficacy of behavioral interventions for youth with diabetes designed to increase consumption of whole grains, fruits, vegetables, and legumes; 2) mediators and moderators of behavior change; and 3) physiological effects of dietary change. Dietary recommendations for persons with diabetes must take into account both the potential benefits dietary change, as well as the feasibility, acceptability, and expected difficulty of implementing such recommendations. Studies to date have relied primarily on either experimental manipulation or traditional dietary education to achieve dietary change, and so provide inadequate information to guide clinical practice with free-living individuals. Thus, findings from this study will address areas that are currently lacking in the knowledge base.