Day One CGM Accuracy Tips from a T1D Dietitian

Jun 12, 2025

Continuous glucose monitors (CGMs) have changed the game for people living with diabetes

But anyone who has worn one knows that the first 24 to 48 hours of a new CGM session can be frustratingly inaccurate. For those relying on these devices, especially anyone using an insulin pump with an algorithm, those early readings can create serious challenges.

A registered diabetes dietitian, certified diabetes educator, and strength coach, has lived with Type 1 diabetes for over 25 years. Through personal experience and his work helping others manage blood sugar, he’s seen just how off those Day 1 CGM readings can be. He’s had readings that were off by as much as 80 to 100 points during the first day of wear.

That kind of inaccuracy isn’t just annoying—it can be dangerous, especially when insulin dosing depends on real-time data. Fortunately, there’s a simple strategy that can help your CGM start off with better accuracy: soak the sensor before activating it.

What Is the CGM “Soak” Method?

Here’s how it works. Right before your current CGM sensor session ends, you apply your new sensor, but you don’t activate it yet. Instead, you let it sit on your body for 6 to 12 hours, allowing it to “soak” or adjust to your interstitial fluid.

This means that for a short period, you’ll be wearing two sensors at once: one that’s still active and a new one that’s getting used to your body. Once your old sensor expires, you start the session on the soaked sensor.

This soaking time can help the new sensor produce more accurate readings right from the start, rather than the usual guessing game of Day 1. While it's a simple trick, it can make a huge difference, especially for those using insulin pumps that automatically adjust dosing based on CGM data.

Why Accuracy Matters on Day 1

For people with Type 1 diabetes and Type 2 diabetes, CGMs are often used alongside insulin pumps that use sophisticated algorithms. These algorithms make real-time adjustments to insulin delivery based on blood sugar readings. But if those readings are wrong, even by a small margin, the system may deliver too much or too little insulin.

That’s why this tip from a Type 1 diabetes dietitian can be such a game-changer. By helping patients and clients avoid inaccurate data on Day 1, the soaking method leads to better control, fewer highs and lows, and more confidence in CGM technology.

The Role of a Diabetes Dietitian in CGM Education

While this tip might seem simple, it’s one of many practical strategies that a qualified diabetes dietitian or certified diabetes educator might share with clients. People working with a T1D dietitian or T2D dietitian benefit from real-world guidance that goes beyond textbook advice.

Not every diabetes care team covers tips like this. And if yours doesn’t, it might be time to seek out a new diabetes educator who understands the latest in diabetes technology and lifestyle strategies.

Type 1 diabetes dietitians and Type 2 diabetes dietitians often go beyond meal planning—they help clients interpret glucose trends, adjust to new devices, and improve overall blood sugar control. Education around CGMs, especially tips for maximizing their performance, is a key part of that support.

That’s what makes this tip about soaking CGM sensors so effective—it’s a small, actionable step that can save a person living with diabetes from days of stress, poor sleep, and blood sugar swings.

Final Thoughts

Getting accurate CGM readings from Day 1 doesn’t have to be hit or miss. The soaking method is a simple and practical solution that any T1D dietitian, T2D dietitian, or certified diabetes educator would recommend for those struggling with CGM inaccuracy.

If your current care team hasn’t mentioned tips like this, it may be worth connecting with a diabetes dietitian who understands the full scope of modern diabetes care, including how to get the most out of your technology.