Glucose: what to watch and what not to

Glucose rising after a meal is normal. What matters are fasting values and averages.

"Spikes" are normal

After a meal, glucose rises and comes back down. That also happens in healthy people, as continuous-sensor studies have shown. A single spike is not a problem.

Reference values

The American Diabetes Association uses these cutoffs: fasting below 100 mg/dL is normal, 100 to 125 indicates prediabetes, and 126 or more on two tests indicates diabetes. Two hours after eating, below 140 is expected. Diagnosis is made by a professional with lab tests, not with an app.

If you have diabetes

Do not fast without talking to your doctor, especially if you use insulin or other glucose-lowering drugs: there is a risk of hypoglycemia.

Sources

• Hall H et al. Glucotypes reveal new patterns of glucose dysregulation. PLoS Biol. 2018;16(7):e2005143.
• American Diabetes Association. Classification and diagnosis of diabetes: Standards of Care in Diabetes. Diabetes Care (actualización anual).

General information; not a substitute for a health professional.