Understanding of glycemic response using contextual data and modeling * a pilot study

Many people in the Western world have an unhealthy lifestyle, including an
unhealthy dietary pattern. Elevated postprandial blood glucose levels, as well
as high variability in glucose levels are associated with major risk for
prediabetes, type II diabetes and cardiovascular diseases. The use of glycemic
index of food products for controlling glycemic responses has limited efficacy.
Zeevi et al., have shown that the glycemic response on food is highly personal
and not directly linked to the glycemic index of food products. Based on a
cohort of 800 people using multiple measurements, a prediction model based on
mainly the microbiome was made. Surprisingly, known factors influencing
glycemic response like stress levels, quality of sleep and physical activity
were not found. A problem with these big cohorts is the quality of data that
is collected, the lack of contextual data and the laboratory setting in which
the data is collected (which doesn*t necessarily reflect real-life).

The proposed research is part of a research program on Personalized Nutrition
and Health (PNH). The ultimate goal of the program is to enhance the health and
wellbeing of people by empowering consumers to choose and maintain an optimal
personalized diet and lifestyle.

The primary goal is to obtain and investigate the added value of real-life high
quality contextual data (e.g. food intake, physical activity, sleep, wellbeing)
to understand and predict the fluctuations in individual glucose levels.

The secondary objective is to define what metrics of glucose profiles can best
be used to personalize lifestyle recommendations with respect to food intake
and physical activity.

During this observational pilot study 24 volunteers will use a continuous
glucose monitor (CGM) to self-monitor their glucose levels. Additionally, their
activity patterns, heart rate and sleep quality and quantity are monitored
using a Philips smartwatch. Furthermore, the participant is asked to register
their food intake and score their wellbeing using a smartphone app.
The duration of the pilot study is 13 days. Since the continuous glucose sensor
requires a 12 hour initialization period, one day before the start of the
pilot, the glucose sensor will be applied on the participants upper arm. At the
first day of the pilot a baseline measurement is performed by giving the
participant and Oral Glucose Tolerance Test (OGTT), the participant is asked to
fast 10 hours before the OGTT. Afterwards the participant is asked to fill in a
satiety questionnaire regarding the OGTT in the HowAmI app. Additionally, the
participant is asked to start wearing the smartwatch and using the apps to
register and photograph their food intake and answer questions regarding their
wellbeing. During the remaining days of the pilot the participant can consume
their normal diet, but the participant is asked to register the food intake and
answer wellbeing questionnaires in the HowAmI smartphone app. Participants will
be asked to maintain a varied diet, but also ensure some repetition (e.g.
consume the same breakfast, lunch and snacks for three days during the
measuring period). To aid subjects in this we will provide them with some
snacks.
After 13 days of self-monitoring a debriefing will take place in which all the
participants can ask questions about the study and their personal data
observations. Furthermore, the participants will return the glucose sensor and
the smartwatch and answer questions about their experiencees with participating
in the study.

The intervention consists of the OGTT. On the first day of the study the
participant will consume an OGTT. The participant can consume the OGTT at home
in the morning of the first day of the study. Before the OGTT is consumed the
participant is asked not to eat or drink anything (besides water) for the last
10 hours. Just before the participant drinks the OGGT a picture of the OGTT
should be taken with the HowAmI app which indicates the time the participant
drinks the OGTT.

Disadvantes of participating in this study can be 1) There are some tasks to
required, e.g. keeping track of food intake and answering the wellbeing
questionnaires. 2) there is a small risk of skin irritation due to the glucose
sensor, if this happens the participant is asked to contact the study leader
and replacement of the sensor will be considered or participation in the study
will be ended if the sensor is removed. 3) A potential risk is concern amongst
participants to learn about health issues they are not familiar with.