Clarke Hypoglycemia Awareness Questionnaire
Also known as: HAQ, Clarke HAQ, Hypoglycemia Awareness Scale
The Clarke Hypoglycemia Awareness Questionnaire is an 8-item instrument designed to identify patients with impaired hypoglycemia awareness—a condition in which diabetic patients fail to perceive early warning symptoms of low blood glucose, substantially increasing their risk of severe hypoglycemia. Developed by Clarke and colleagues in 1995, it is the most widely used screening tool for this dangerous complication in type 1 diabetes and in insulin-treated type 2 diabetes populations.
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When to use it
The Clarke HAQ is indicated for: (1) Routine screening in all type 1 diabetes patients at initial endocrinology visit and periodically (annually or biannually) thereafter; (2) Insulin-treated type 2 diabetes patients, particularly those on intensive regimens; (3) Evaluation of patients with unexplained severe hypoglycemia episodes or frequent nocturnal hypoglycemia; (4) Identification of candidates for continuous glucose monitoring technology and insulin pump therapy; (5) Research studies investigating hypoglycemia awareness, risk factors for HAAF, and interventions to restore awareness. Increasingly integrated into diabetes management algorithms and clinic decision-support systems.
Strengths & limitations
- Rapid screening: 8 items require <5 minutes; feasible for routine clinical use during standard diabetes visits without additional staff or equipment burden.
- Strong prognostic value: Impaired awareness score strongly predicts subsequent severe hypoglycemia risk; discriminates high-risk from low-risk patients with sensitivity ~75-85% and specificity ~70-80%.
- Clinical actionability: Clearly identifies patients who warrant intensive glucose monitoring (CGM), technology interventions (insulin pumps), or behavioral interventions (hypoglycemia avoidance training).
- Universally adopted: Recommended by American Diabetes Association, European Association for the Study of Diabetes, and Endocrine Society; standardized across international diabetes programs.
- Subjective recall: Relies on patient memory of recent hypoglycemic episodes; patients with infrequent hypoglycemia may have limited recent experience to report, introducing uncertainty.
- Symptom heterogeneity: Individual patients vary in which symptoms predominate (some experience primarily adrenergic symptoms like tremor; others experience neuroglycopenic symptoms like confusion); questionnaire equally weights all symptom types.
- Cognitive capture: Patients may overestimate or underestimate symptom recognition; cognitive biases (optimism bias, anchoring to recent severe episode) can distort responses.
- Imperfect correlation with objective hypoglycemia frequency: Some patients report impaired awareness but experience relatively few asymptomatic lows on CGM; others report preserved awareness but have frequent hypoglycemic episodes without symptoms—actual measurement-based categorization occasionally conflicts with self-reported awareness.
Frequently asked
What score is safe to drive with?
No absolute safe threshold. Preserved awareness (score ≥4) does not guarantee driving safety; impaired awareness (score ≤3) substantially elevates risk. Combined assessment using Clarke HAQ, documented hypoglycemia frequency (from glucose logs or CGM), and patient's glycemic target all inform clinical driving counseling. Recommendations vary by jurisdiction; some require CGM for impaired-awareness patients operating vehicles. Discuss risk with patients and consider referral to occupational health.
Can hypoglycemia awareness be restored?
Yes, partially. Strict hypoglycemia avoidance for 2-6 weeks can restore some symptom recognition in mild impairment, though complete restoration is uncommon in patients with long disease duration or after multiple hypoglycemic episodes. Newer interventions (hybrid closed-loop insulin pumps, islet transplantation, sympathomimetic agents) show promise but are not standard care. CGM enables safe living with impaired awareness by providing automated low glucose alerts.
Should the questionnaire be repeated if score is normal?
Yes. Recommended rescreening every 1-2 years; more frequent (6-12 months) if multiple risk factors for HAAF (long duration, intensive therapy, frequent hypoglycemia episodes). Awareness can deteriorate over time; periodic screening detects early changes warranting intervention.
Does the score predict future severe hypoglycemia risk numerically?
Impaired awareness (score ≤3) is associated with 3-5 fold increased risk of severe hypoglycemia compared to preserved awareness; however, individual risk varies widely based on glycemic control, hypoglycemia frequency, and behavioral factors. The questionnaire is a categorical screener (high vs. low risk), not a precise numerator of risk. Objective glucose monitoring provides more granular risk prediction.
Sources
- Clarke, W. L., Cox, D. J., Gonder-Frederick, L. A., Julian, D., Schlundt, D., & Polonsky, W. (1995). Reduced awareness of hypoglycemia in adults with IDDM: A prospective study of hypoglycemic frequency and associated symptoms. Diabetes Care, 18(6), 517-522. DOI: 10.2337/diacare.18.4.517 ↗
- Gold, A. E., MacLeod, K. M., Frier, B. M., et al. (2012). Frequency of severe hypoglycemia in patients with type 1 diabetes with impaired awareness of hypoglycemia. Diabetes Care, 17(9), 697-703. link ↗
How to cite this page
ScholarGate. (2026, June 3). Clarke Hypoglycemia Awareness Questionnaire. ScholarGate. https://scholargate.app/en/endocrinology/hypoglycemia-awareness-questionnaire
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