What moves your glucose
Does Poor Sleep Raise Your Blood Sugar?
Poor sleep is linked to higher blood sugar and to the body responding less well to insulin. The evidence is strongest for how sleep loss affects insulin sensitivity, and weaker for what it does to any one night’s CGM trace.
On this page
What the research shows
In an NIDDK Q&A, sleep researcher Eve Van Cauter explains that short, irregular or repeatedly interrupted sleep all promote glucose intolerance. In controlled lab studies of healthy adults, too little sleep reduced insulin sensitivity by about 25% to 30% after as little as four to five days.
The Sleep Foundation reports that even partial sleep deprivation over one night increases insulin resistance, and that cortisol, a stress hormone, rises with sleep deprivation.
Those lab studies were mostly in young, healthy adults. They show a mechanism, not what happens to you on a given night.
What a CGM study of adults with type 1 found
A study in The Journal of Clinical Endocrinology & Metabolism, summarized by Cleveland Clinic, followed 42 adults aged 18 to 30 with type 1 diabetes for a week, tracking sleep and glucose with a CGM. Within the same person, lower sleep efficiency was associated with less time in range and more time high. More sleep disruptions and more time awake after falling asleep were associated with higher glucose variability.
It was a small, one-week study, and its findings are associations rather than proof of cause. They concern sleep quality and timing, not total hours slept.
The link runs both ways
The Sleep Foundation cites a study in which people with type 2 diabetes and higher blood sugar slept more poorly, and says researchers aren’t certain why. Low blood sugar at night can also disturb sleep. Signs the Sleep Foundation lists, citing NIDDK, include nightmares, crying out in sleep, heavy sweating, and irritability or confusion on waking.
Sleep apnea
The NIDDK Q&A says obstructive sleep apnea affects about two-thirds of people with type 2 diabetes, and that the more severe it is, the lower the insulin sensitivity.
If you suspect a sleep problem such as sleep apnea, that is a conversation for your care team.
Seeing it in your own data
Dia reads sleep from Apple Health, shows it next to your glucose, and looks across your days for how a short or broken night lines up with the day after. It describes the pattern. It doesn’t tell you what to change.
Questions
How much does one bad night affect blood sugar?
It varies by person. The Sleep Foundation reports that even partial sleep deprivation over one night increases insulin resistance, but none of the pages we cite put a number on what that means for a CGM trace. Your own data is the better guide.
Does sleep affect type 1 and type 2 differently?
The NIDDK page focuses on type 2, and the CGM study we cite looked at adults with type 1. Neither compares the two, so we can’t say.
Sources
- NIDDK Diabetes Discoveries & Practice Blog. The Impact of Poor Sleep on Type 2 Diabetes (Q&A with Eve Van Cauter, PhD). March 17, 2021.
- Sleep Foundation. Blood Sugar and Sleep: How Sleep Affects Glucose Levels.
- Cleveland Clinic Consult QD. Exploring the Relationship Between Sleep Amount and Type 1 Diabetes. April 29, 2022.