Continuous Glucose Monitors (CGM) for Type 2 Diabetes (T2D) Risk Evaluation

The purpose of this research study is to determine whether continuous glucose monitors (CGM) are a safe, effective, and acceptable way to evaluate type 2 diabetes risk in youth as compared to the standard 2-hour oral glucose tolerance test (OGTT).

This study will involve wearing a CGM, wearing a physical activity tracker, responding to surveys, and completing at-home glucose and mixed food challenge while wearing the CGM. Subjects will also be asked to complete an interview by phone or videoconference after wearing the CGM.

Youth-onset type 2 diabetes (T2D), an increasingly common and aggressive disease that disproportionately impacts racial and ethnic minorities, presents several diagnostic challenges. The rapid loss of glycemic control soon after T2D diagnosis makes early identification an important goal in pediatrics, and risk-based screening has been recommended for children for over two decades. However, the screening tests currently used in practice, including hemoglobin A1c (HbA1c), fasting glucose, and 2-hour oral glucose tolerance test (OGTT), have significant drawbacks. Real-time continuous glucose monitors (CGM) are promising new tools for risk stratification in individuals with dysglycemia. These patient-worn medical devices measure interstitial glucose every 5 minutes and offer glimpses into an individual's everyday life, which may include consumption of carbohydrates in amounts larger than that assessed in an OGTT, enhancing test sensitivity. Whether use of CGMs to evaluate type 2 diabetes risk in free-living youth is feasible and acceptable to patients and families is unknown. Assessment of CGM with standardized, but practical, home-based glucose and mixed-meal challenges is needed to determine facilitators and barriers to use of this technology-driven approach in clinical practice. Without advancement in the approach to screening for youth-onset T2D, there is ongoing risk of failure to understand which individuals are at highest risk for complications and could benefit the most from intervention early in the disease process.

In this single-arm prospective study, participants will attend one in-person study visit to complete 2-hour oral glucose tolerance test after overnight fast. Participants will wear a continuous glucose monitor and a wrist-worn actigraphy device for physical activity and sleep measurement for 10 days beginning on the day of the study visit, then return the monitors by mail. During the 10 day wear period, participants will respond to text message-based surveys to document food intake, physical activity, and sleep times and will complete two at-home challenges: 1) glucose challenge using study-provided glucose beverage that is identical to that they consume during clinical oral glucose tolerance test; and 2) food challenge with mixed carbohydrate/fat/protein-containing food of their choice. Glucose trends during these at-home challenges will be compared with oral glucose tolerance test obtained during the study visit. Individual interviews will be conducted upon completion of CGM wear to assess acceptability of the use of at-home glucose challenge and CGM wear as a strategy to evaluate diabetes risk in youth.

Eligibility Criteria:
Inclusion Criteria:

* Any gender, age 8-18 years
* Tanner 2 or higher pubertal development
* Overweight or obese (BMI ≥85th percentile for age/sex, or ≥ 25 kg/m2 for participants =18 years)
* A) No previously documented abnormal HbA1c or glucose but at higher risk for T2D based on race/ethnicity (Black, Hispanic, Asian, Native American, Pacific Islander), diagnosis with dyslipidemia, hypertension, polycystic ovary syndrome, presence of acanthosis nigricans, or first degree relative with T2D; or B) previously documented (within 6 months) HbA1c 5.7-7.0%, fasting glucose ≥100 mg/dL, or 2-hour plasma glucose on OGTT of ≥140 mg/dL
* Consent (adult subjects), parental/guardian permission (if applicable), assent (if applicable)
* Willingness to wear ActiGraph watch and CGM continuously for 10 day study duration

Exclusion Criteria:

* Current or recent (within 1 month) use of diabetes-related medication
* Current use of hydroxyurea (due to interference with CGM)
* Known type 1, cystic fibrosis-related, or medication-induced diabetes
* Potential subject unable to speak or read in English
* Severe cognitive impairment
* Current or previous pregnancy