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Let’s Talk About Your Donated Data

November 2nd, 2017

Over the summer, Tidepool launched the Tidepool Big Data Donation Project, helping you donate your anonymized diabetes data to research. Since the Project’s launch, we’ve been blown away by the community’s response—more than 1,100 datasets have been donated, with more coming in every day.

We’ve been working with Ed Nykaza, a longtime contributor to Tidepool and father of Leah, who has type 1 diabetes (T1D), to help us analyze and understand this data. The results of his work are fascinating!

This post presents the data in mmol/L. Click here if you’d like to read this data in mg/dL.

The Basics

If you’re a Tidepool user, you’re probably familiar with the blood glucose (BG) distribution chart on the top left corner of your Basics screen. To jog your memory, it looks like this:

You may have wondered how you’re doing compared to other users. Well, first of all, you’re one of kind and there’s no one quite like you!

But based on the first 354 Tidepool users who have donated their CGM (continuous blood glucose) data, we can give you an idea of averages across each age group.

Summary Blood Glucose Analysis from Tidepool Big Data Donation Project

When reading the chart above, it’s important to note that the blood glucose numbers for Tidepool users in every age group tend to be lower than comparable numbers for the diabetes population overall. For more on that, see the “Bias” section at the end of this blog post.

The People Behind the Data

Before we dive deeper, let’s take a moment to better understand the demographics of our anonymized data donors.

Current Age of Donors from Tidepool Big Data Donation Project

Diagnosis Age from Tidepool Big Data Donation Project

Years Living With Diabetes from Tidepool Big Data Donation Project

Looking at donors’ age of diagnosis and number of years living with diabetes creates some really cool groupings.

For example, below you can see a cluster of users younger than 18, then a gap during the college years, then another cluster after college-age, and finally, a surprising number of datasets into the later years.

This sheds light on not just the diversity of the datasets, but also the diversity of the Tidepool community!

Age and Years With Diabetes Distribution from Tidepool Big Data Donation Project

Nerdy Notes About This Data

We’re about to dive into some trends in glucose levels. Before we do, there are a couple nerdy things to note about this data.

  1. “N” is one year of data donated by a Tidepool user. A single user may have donated more than one year of data. For example, a 35 year old who has donated three years of data from when they were 33, 34, and 35 years old. As such, they will contribute N=2 to the 30-34 bucket and N=1 to the 35-39 bucket.
  2. We are using the AACE and ACE consensus of target blood glucose being between 3.9 – 10 mmol/L. We know each person with diabetes sets their own personal target ranges, that’s why it’s a customizable setting within your Tidepool profile. For simplicity, we’re applying the 3.9 – 10 mmol/L range to all of this data.

Time in Range

Now, let’s start by looking at average glucose levels and time in range, by age group.

It’s interesting to see how often the different age groups are staying in the target range of 3.9 – 10 mmol/L.

Look at the incredible change from the 21-24 year age group to the 25-29 year age group. Those 25-29 years olds appear to make a tremendous comeback, going from 63% to 74% time in range. That’s, on average, an additional 2 hours, 38 minutes in target range per day.

There are so many incredible findings in just these two charts. What other insights do you see from this data?

And how about the datasets from folks between 65-85 years old. 82% time in range? What’s their secret?! (…a possible topic for future blog post, perhaps?)

Time Below Target

Now let’s look at the other side. How much time are Tidepool data donors spending in hypoglycemia?

Data donated by younger adults shows they experience more time in hypoglycemia than other age cohorts.

Specifically, the 30-34 year old and 35-39 year old cohorts in particular spend 5.8% and 5.5% of their time below 3.9 mmol/L. That’s about 80 minutes per day, on average!

These same cohorts, age groups 30-34 and 35-39, also spend about 24 minutes per day, on average, below 3.0 mmol/L. That’s a real cost of managing life with diabetes.

Many of us at Tidepool identify with this as our own personal experience. We get it. Trying to keep your diabetes under control is hard work.

Time Above Target

What about the other side of spectrum, time above target range?

If you’re the parent of a 15-year-old with diabetes and have noticed that their BGs seem to be above target more than before, you are not alone.

According to the donated datasets, 12-14 year olds spend on average about 3 hours per day (12.7%) above 13.9 mmol/L. That number jumps to about 4 hours per day (16.3%) for the 15-17 year olds.

Population Bias

Let’s take a moment to acknowledge bias. Bias is an over- or under-estimation of a population sample that prevents objective consideration of an issue or situation. Bias shows up in our data in at least a couple of ways:

  1. Donors to the Tidepool Big Data Donation Project are self-selecting (they volunteered); they are not randomly selected.
  2. They are also much more likely to be on a pump and/or a CGM than the average person with diabetes, which means this data is not necessarily representative of the general public, especially those not on devices. We know from the T1D Exchange, for example, that folks on pump and CGM tend to have A1C improvements over folks on MDI without CGM.

One place we see this bias is when we compare estimated A1C of the Tidepool sample population (based on the formula: eA1C = ((average glucose * 18.01559) + 47.6) / 28.7 ) to the chart of A1C by age cohort presented by the T1D Exchange based on its Registry. We found that, while the curves are similar, estimated A1C for the Tidepool sample population is consistently 1.0% – 2.0% lower than that of the T1D Exchange Registry population.

A1c Comparison with T1D Exchange Registry from Tidepool Big Data Donation Project

Our Next Steps

As excited as we are to help the community better understand real life with diabetes, we’ve only scratched the surface with this data. This post only examines one small, but important set of insights based on CGM data. We’ll look at more insights, including those based on insulin dosing, in upcoming posts.

But what about you? What comes to your mind when you look through these charts? Does this data resonate with you? Why or why not? What other questions would you like us to explore next? Leave a comment or send an email to bigdata@tidepool.org and let us know what you think!

Be sure to check out this guide if you’d like to donate your own diabetes data to the Tidepool Big Data Donation Project.

As for us? We’re just getting started.

Yours in big data,
Brandon & Ed


Bring this data into your next project

If you think your company would benefit from collaborating with Tidepool to better understand the needs of people with diabetes, contact us at bigdata@tidepool.org.

If you are a citizen scientist or independent researcher and need real device data to help with your project, you can also email us at bigdata@tidepool.org. We’ll have an exciting announcement for you soon. Stay tuned.

Technical notes on this data

  • Participants donated their data via the Tidepool Big Data Donation Project.
  • Tidepool users use the Tidepool Uploader and Tidepool Mobile to upload their data.
  • Data presented here is based on CGM usage. Tidepool supports both Dexcom and Medtronic CGMs. The data here includes both. Since device makers can be sensitive to comparative studies, we won’t be making a distinction between different device types.
  • Our analysis tech stack includes Project Jupyterpythonpandas and matplotlib.

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