Dehydration is one of the most overlooked causes of high blood sugar — and one of the easiest to fix.
The mechanism
Less water in your bloodstream concentrates everything in it, including glucose. A mild fluid loss of 2% body weight can raise blood glucose by 20–40 mg/dL.
Worse, dehydration triggers cortisol release, which signals the liver to dump more glucose into circulation. The cycle becomes self-reinforcing: high glucose causes more urination, which causes more dehydration, which causes higher glucose.
Daily water targets
- **Baseline**: half your body weight in ounces (150 lb → 75 oz)
- **Diabetes**: add 16 oz if glucose is consistently above 180
- **Hot weather/exercise**: add 16–32 oz
- **Caffeine drinkers**: add 8 oz per cup of coffee/tea
Signs of dehydration
- Dark yellow urine
- Headache
- Dry mouth
- Reduced urine output
- Fatigue
- Glucose rising for no clear reason
Best drinks
- Water (still or sparkling)
- Unsweetened tea (green, black, herbal)
- Black coffee (in moderation)
- Bone broth
- Electrolyte drinks with no sugar (LMNT, Ultima)
- Sparkling water with lime/cucumber
Avoid
- Sugary drinks (obvious)
- Diet sodas as primary hydration (use sparingly)
- Sports drinks (mostly sugar)
- Alcohol (net dehydrating)
Electrolytes matter
Low sodium and potassium can mimic dehydration. If you sweat a lot or eat low-carb (which is naturally dehydrating), add a pinch of salt to your water or use an electrolyte mix.