Blood Glucose Variability in Obese Youth Participating in a Lifestyle Modification Program

Healthy lifestyle intervention programs aim to increase exercise and teach youth and about healthier dietary options, in hopes of avoiding obesity complications such as diabetes, and addressing the root causes of obesity. The program entitled Bright Bodies: A Lifestyle Intervention Program for Obese Youth, has been tested rigorously, showing significant improvements in body mass index and insulin resistance at both 1 and 2 years after the program and reversal of early abnormalities in glucose metabolism. While abnormalities on standardized oral glucose tolerance testing are well described in obese youth, this test may not reflect the "real life" glycemia changes in obese children. Understanding early glycemic changes in obese youth is important to better identify those at risk and strategize effective treatment plans, to avoid progression to prediabetes and diabetes. Thus the use of a continuous glucose monitor (CGM) may be a helpful adjunct to understanding the disease and therapy approaches in these patients.

A CGM is a device inserted under the skin on the abdomen which monitors glucose levels every 5 minutes, recording this information. CGM is commonly worn by kids with type 1 diabetes. The study will allow collection of information on glucose variability in much greater detail than can be seen from intermittent fingerstick glucose values or from an oral glucose tolerance test. Given the widespread epidemic of obesity and its complications, the ability to illustrate glycemic variability in obese youth is key to delineating risk categories and optimizing treatment. While lifestyle modification programs can be effective in improving measures of insulin sensitivity and OGTT results, their effect on real life glucose values has not been described. Hence the current study, aims to describe day-to-day glycemic variation in obese youth using CGM.

All enrolled subjects will wear a CGM for up to 7 days prior to initiation of the Bright Bodies program, and for up to 7 days at the end of the program. Additionally subjects will complete a food record and report exercise during both study periods. The study periods will take place during the 2 months prior to and the 2 months after completing the Bright Bodies program. The study will be explained to volunteers who meet eligibility criteria and informed consent/assent will be obtained. Demographic data will be recorded. Medical history will be obtained and a brief physical exam may be performed. Height, weight, BMI, percent body fat, fat mass, and fat free mass will be measured.

After enrollment subjects will meet with study personnel and learn how to keep a food record, with intermittent phone contact by study personnel to optimize food record compliance. They will also be asked to record exercise and any medications taken. A blinded CGM will be inserted at the beginning of each study period. Subjects will be educated regarding the CGM, including the requirement to measure blood glucose levels with a glucometer 3 times a day, at least every 12 hours (ideally on waking in the morning before eating, before dinner, and before bedtime), to calibrate the sensor. Subjects will be given a glucometer to obtain fingerstick blood sugar values and receive instruction regarding its use.

During the follow up visits the CGM will be removed, and the CGM and glucometer will be downloaded and collected. The food record will be collected.