By: Kathryn Gentile-Alvarez, MS, ACSM-CEP, CDCES — Director of Open-Source Technology, Integrated Diabetes Services
If you have ever eaten the same meal, taken the same insulin, followed the same routine, and still ended up with a completely different blood sugar result, you are not imagining things.
I'll never forget one of the most important things I learned listening to Alicia back when I was an intern. She was telling someone that diabetes is as much of an art as it is a science and it's also a bit of pixie dust. She proceeded to say the definition of insanity is "doing the same thing over and over and expecting different results." Diabetes puts that definition to the test by showing us that different outcomes are not a failure of effort, but a reflection of a constantly changing body.
At Integrated Diabetes Services, this is one of the most common frustrations we hear: "I didn't change anything, my blood sugar was perfect one day and the next all over the place, why?"
Here is the truth most people are not told. Diabetes is not always a math, settings, or timing problem. It can be a "biology" variable. And biology changes every day.
Why the Same Day Rarely Produces the Same Numbers (to name a few)
Even when carbohydrate, protein, and fat intake and insulin dosing remain consistent, many other factors do not.
- Stress and emotional load can raise glucose levels, sometimes hours after the stressful event has passed.
- Sleep quality plays a major role in insulin sensitivity. Poor or disrupted sleep can make the next day's blood sugars harder to manage, even when everything else looks unchanged.
- Exercise affects glucose differently depending on timing, type and intensity.
- Hormonal shifts, including illness, cortisol release, growth hormone, menstrual cycles, and dawn phenomenon, all influence blood sugar in ways that are not always obvious at the moment.
- Insulin absorption varies based on infusion site location, scar tissue, insulin age, and environmental factors such as heat, cold, or pressure. Even when dosing is correct, absorption may not be consistent.
- Digestion speed also matters. Fat, protein, fiber, hydration, and gut motility all affect when glucose appears in the bloodstream, not just how much appears.
Blood glucose is regulated by a complex network of overlapping variables rather than a single controllable factor. Even this list only scratches the surface of the variables involved.
Why "Trying Harder" Usually Makes Things Worse
When blood sugars feel unpredictable, many people respond by making frequent corrections, aggressively reducing carbohydrates, or constantly adjusting settings.
Unfortunately, these reactions often increase variability rather than reduce it. Knee jerk adjustments often do not reflect the day to day overall trends. Our blood glucose outcomes respond better to pattern recognition and we want to ensure that's where we focus our attention.
What Helps When Numbers Feel Random
Instead of asking, "What did I do wrong?" it can be more helpful to ask:
- Is this a one-time fluctuation or a recurring pattern?
- Did anything change earlier that could explain what I am seeing now?
At IDS, we focus on identifying trends over time, minimizing unnecessary self-blame, and making thoughtful, targeted changes. Our goal is to help people use their data effectively without becoming overwhelmed by it.
