BeAM Value

Why use it

Provides a simple, actionable metric to guide basal insulin dose adjustments. Helps identify the dawn phenomenon (early morning hyperglycemia due to cortisol and growth hormone surges) and differentiates it from insufficient basal insulin dosing. Facilitates structured conversations between patients and clinicians about basal insulin efficacy.

About

The BeAM value (Bedtime and Morning blood glucose difference) is a practical tool used in diabetes management to evaluate the overnight glycemic trajectory and the efficacy of basal insulin therapy. It is calculated by subtracting the fasting morning blood glucose from the bedtime blood glucose. A positive BeAM value indicates the expected overnight glucose-lowering effect of basal insulin; a negative or near-zero value may indicate insufficient basal insulin coverage, the dawn phenomenon, or the Somogyi effect. The BeAM value provides a simple, single-number summary of how blood glucose changes overnight and can guide basal insulin dose titration decisions in clinical practice.

When to use

• Patients with type 1 or type 2 diabetes on basal insulin therapy
• Identifying causes of unexplained fasting hyperglycemia
• Guiding basal insulin dose titration decisions
• Assessing overnight glycemic patterns before or after adjusting basal insulin
• Patient education on basal insulin function and overnight glucose behavior

Formula

Pearls & pitfalls

• A BeAM ≥ 20 mg/dL is often cited as the threshold indicating adequate basal insulin effect (meaningful glucose lowering during sleep).
• Negative BeAM (morning glucose > bedtime glucose) is a common cause of patient frustration — they wonder why fasting glucose is high despite taking their basal insulin.
• The dawn phenomenon results from early morning surges of counter-regulatory hormones (cortisol, growth hormone), causing glucose to rise between 3–8 AM regardless of basal insulin dose.
• The Somogyi effect (nocturnal hypoglycemia followed by rebound hyperglycemia from counter-regulatory response) can also produce a negative BeAM — check for nocturnal hypoglycemia symptoms.
• Continuous glucose monitoring (CGM) provides much more detailed overnight data than BeAM alone, and should be used when patterns are unclear.
• BeAM should be evaluated over several consecutive days to identify a meaningful pattern — a single day measurement has limited value.
• Different basal insulins have different action profiles — NPH peaks overnight (risk of nocturnal hypoglycemia), while insulin glargine/degludec are relatively peakless.

Next steps

BeAM ≥ 20 mg/dL: Basal insulin is having meaningful overnight glucose-lowering effect. If fasting glucose remains above target, consider carefully increasing basal dose. BeAM 1–19 mg/dL: Minimal overnight effect — evaluate dose, timing, and injection site. BeAM ≤ 0 (negative): Morning glucose exceeds bedtime glucose — investigate dawn phenomenon, Somogyi effect, insufficient basal coverage, or high-carbohydrate evening intake. Consider continuous glucose monitoring (CGM) for detailed overnight pattern assessment.

Evidence

The BeAM value has been used in clinical practice and diabetes management protocols to characterize basal insulin efficacy and guide titration algorithms. Referenced in insulin titration studies including the Treat-to-Target trial and follow-up analyses. Used to evaluate insulin detemir vs. NPH overnight glucose profiles by Owens et al. (2006).

References

1. Riddle MC et al. The Treat-to-Target Trial: randomized addition of glargine or human NPH insulin to oral therapy of type 2 diabetic patients. Diabetes Care. 2003;26(11):3080-3086. — link
2. Owens DR et al. Differential effects of bedtime administration of insulin detemir and NPH insulin on basal insulin requirements and morning blood glucose profiles. Diabet Med. 2006;23(11):1180-1186. — link