Blood Sugar Fluctuations and Their Seldom-Considered Causes
June 5, 2026 · By Dr. Sam Fereidouni, MD, MHSA · Diabetes
You're eating the same meals, taking the same medication - and your glucose readings are suddenly all over the map. Before you blame willpower, consider the causes we investigate when a patient's numbers wander without an obvious dietary reason.
1. Sleep debt
Even a few nights of short sleep measurably increases insulin resistance. If your fasting numbers creep up during a stressful week, the fix may be your bedtime, not your medication dose.
2. Stress hormones
Cortisol and adrenaline raise blood glucose by design - useful for escaping danger, unhelpful during a difficult month at work. Patients are often surprised that a family emergency shows up in their meter before it shows up anywhere else.
3. Illness and inflammation
An infection - even a "minor" one like a dental abscess or a slow-healing cut - drives glucose up. Unexplained highs are sometimes the first sign of an infection you haven't noticed. This is one reason diabetic foot checks matter so much.
4. Medication timing and interactions
Steroid injections, certain blood pressure medications, and even some over-the-counter decongestants move blood sugar. So does taking your diabetes medication at inconsistent times. Bring every bottle to your next visit - we reconcile the whole list.
5. The dawn phenomenon
A morning surge of hormones raises glucose before breakfast in many people with diabetes. If your fasting number is your worst of the day, this may be physiology, not failure - and there are specific strategies for it.
What we do about it
Individualized care means we don't hand you a generic sheet - we look at your data, your sleep, your stress, your medication list, and increasingly your CGM trace, and find your pattern. If your numbers have been wandering, bring two weeks of readings to your next visit, or ask us about a continuous glucose monitor trial.
Dr. Fereidouni has specialized in diabetes care since 2004, has served as a clinical investigator in diabetes research, and conducts educational programs for other physicians on diabetes care management.