Optimal - The Blog

March 23, 2023

How Low Can You Go? When is blood glucose too low?

Blood glucose must be maintained within a fairly tight range in order to provide a consistent source of energy for cells throughout the body, especially the brain.

Blood glucose below 70 mg/dL (3.9 mmol/L) usually indicates hypoglycemia and can be accompanied by unpleasant symptoms, including irritability, confusion, dizziness, and even loss of consciousness. If blood glucose drops too low, the body releases hormones, including cortisol and epinephrine, to bring levels back up. These hormones can also cause unpleasant symptoms, including shakiness and anxiety (ADA Hypoglycemia 2022). Blood glucose may then increase to levels above normal, causing rebound hyperglycemia (ADA Glycemic Targets 2022). For someone with diabetes, a nighttime glucose of 90-150 mg/dL (5.0-8.3 mmol/L may be acceptable (ADA Standards of Medical Care 2022).

If hypoglycemia occurs during sleep, the quality and duration of sleep can be negatively affected. Research indicates that nocturnal hypoglycemia can inhibit slow-wave sleep, a stage of sleep needed for the restoration of the body and memory support in the brain (Lui 2016). Low blood glucose should be treated with a snack containing carbohydrates to bring blood glucose levels up to normal (ADA Hypoglycemia 2022).

Eating consistently throughout the day and incorporating a balanced snack at night can help maintain nocturnal blood glucose levels. A healthy snack should contain protein, carbohydrate, healthy fat, and fiber. For example, apple slices with peanut butter, berries and nuts, or hummus with vegetables and whole grain crackers would be ideal nighttime snacks (ADA Snacks 2022).

Some individuals may experience symptoms of hypoglycemia at levels above 70 mg/dL (3.9 mmol/L). Care plans should be individualized and take into account a person’s medical history, current health status, exercise frequency and intensity, and any medications or supplements they may be taking.


American Diabetes Association. "Glycemic Targets." Diabetes.org, American Diabetes Association, 2022

American Diabetes Association. "Hypoglycemia (Low Blood Glucose)." Diabetes.org, American Diabetes Association, 2022

American Diabetes Association. Snacks. Diabetes.org, American Diabetes Association, 2022

American Diabetes Association. Standards of Medical Care in Diabetes—2022. Diabetes Care. 2022;45(Suppl 1):S3-S54. doi: 10.2337/dc22-S001.

Lui MM, et al. "Impact of nocturnal hypoglycemia on sleep in patients with type 2 diabetes." Journal of Diabetes Science and Technology, vol. 10, no. 5, 2016, pp. 1, 105-1, 111. doi: 10.1177/1932296816667312.

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