Frequency of biochemical hypoglycaemia in adults with Type 1 diabetes with and without impaired awareness of hypoglycaemia: no identifiable differences using continuous glucose monitoring

• Published in: Diabetic medicine Vol. 27; no. 6; pp. 666 - 672
• Main Authors: Choudhary, P., Geddes, J., Freeman, J. V., Emery, C. J., Heller, S. R., Frier, B. M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2010; Blackwell
• Subjects: Adult; Awareness - physiology; biochemical hypoglycaemia; Biological and medical sciences; Blood Glucose - analysis; Blood Glucose Self-Monitoring; continuous glucose monitoring; Diabetes Mellitus, Type 1 - complications; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; hypoglycaemia awareness; Hypoglycemia - epidemiology; Hypoglycemia - etiology; Male; Medical sciences; Middle Aged; Risk Factors; severe hypoglycaemia; Statistics as Topic; Surveys and Questionnaires; Time Factors; Type 1 diabetes; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Endocrinopathy; severe hypoglycaemia; Continuous; Awareness; Autoimmune disease; Biochemistry; Continuous Glucose Monitoring System; hypoglycaemia awareness; Adult; biochemical hypoglycaemia; Nutritional status; Human; Immunopathology; Obesity; Nutrition; Nutrition disorder; Metabolic diseases; Hypoglycemia; Surveillance; Type 1 diabetes; Frequency; Severe; continuous glucose monitoring; Endocrinology; Glycemia
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/j.1464-5491.2010.03006.x

Diabet. Med. 27, 666–672 (2010) Objective  Impaired awareness of hypoglycaemia (IAH) is a major risk factor for severe hypoglycaemia in Type 1 diabetes. Although biochemical hypoglycaemia is asserted to be more frequent in IAH, this has not been estimated accurately. The aim of this study was to use Continuous Glucose Monitoring (CGM) to quantify hypoglycaemia in IAH and evaluate its use in identifying impaired awareness of hypoglycaemia. Methods  Ninety‐five patients with Type 1 diabetes were classified as having normal (n = 74) or impaired awareness (n = 21) using an established method of assessing hypoglycaemia awareness. Hypoglycaemia exposure was assessed prospectively over 9–12 months using weekly 4‐point capillary home blood glucose monitoring (HBGM), 5 days of CGM and prospective reporting of severe hypoglycaemia. The frequencies of biochemical and severe hypoglycaemia were compared in patients with normal and impaired awareness of hypoglycaemia. Results  Patients with impaired awareness had a 3‐fold higher incidence of severe hypoglycaemia than those with normal awareness [incidence rate ratio (IRR) 3.37 (95% CI 1.30–8.7); P = 0.01] and 1.6‐fold higher incidence of hypoglycaemia on weekly HBGM [IRR 1.63 (95% CI 1.09–2.44); P = 0.02]. No significant differences were observed with CGM [IRR for sensor glucose ≤ 3.0 mmol/l 1.47 (95% CI 0.91–2.39); P = 0.12; IRR for sensor glucose ≤ 2.2 mmol/l 1.23 (95% CI 0.76–1.98); P = 0.40]. Conclusions  Patients with Type 1 diabetes with impaired awareness had a 3‐fold higher risk of severe hypoglycaemia and 1.6‐fold higher incidence of biochemical hypoglycaemia measured with weekly glucose monitoring compared with normal awareness, but 5 days of CGM did not differentiate those with impaired from those with normal awareness.