Unrecognized hypo- and hyperglycemia in well-controlled patients with type 2 diabetes mellitus: the results of continuous glucose monitoring.
The aim of this study was to determine the prevalence and extent of glycemic excursions (hypo- and hyperglycemic) in elderly patients with well-controlled type 2 diabetes using a Continuous Glucose Monitor System (CGMS) (Medtronic MiniMed). Elderly patients (>65 years old) with type 2 diabetes were recruited if their glycosylated hemoglobin (HbA1c) was <7.5% and if their oral hypoglycemic therapy included a sulfonylurea. Patients were asked to undergo two consecutive 72-h periods of continuous glucose monitoring at baseline and then again at 1 month (total 288 h). Patients were asked to record four self-monitored capillary blood glucose levels each day for calibration of the monitor and also to record meal times, exercise, and symptoms of hypoglycemia. The number of hyperglycemic (>144 mg/dL), hypoglycemic (<50 mg/dL), and borderline-hypoglycemic (50-65 mg/dL) events were determined (an event was defined as a glucose value that persisted for at least 15 min with or without symptoms). Twenty-five patients (21 men, four women) 73.9 +/- 4.4 years old with an HbA1c of 6.2 +/- 0.8% were each monitored for an average of 187.57 h. The mean glucose values were: fasting, 139 +/- 40 mg/dL; 2 h post-breakfast, 167 +/- 58 mg/dL; 2 h post-lunch, 157 +/- 53 mg/dL; and 2 h post-dinner, 149 +/- 49 mg/dL. Twenty patients (80%) experienced a total of 103 hypoglycemic events, and 14 of these patients experienced 54 events where the glucose levels were </=40 mg/dL. Twenty-four patients (96%) experienced borderline-hypoglycemia (n = 229 events). Patients experienced a mean of 0.62 +/- 0.72 episodes of hypoglycemia (interstitial glucose <50 mg/dL) per day (four to five episodes overall), 0.35 +/- 0.6 episodes per day where the interstitial glucose was </=40 mg/dL (two to three episodes overall), and 1.37 +/- 1.22 episodes of borderline-hypoglycemia (nine to 10 episodes overall). Each episode of hypoglycemia persisted for 78 +/- 73 min, and borderline-hypoglycemia for 45 +/- 11 min. Patients were hypoglycemic 3.3% of the time and borderline-hypoglycemic 3.7% of the time. No episode of hypoglycemia was recorded by any patient in his or her daily diary. High postprandial glucose values (>144 mg/dL 2 h postprandial) were recorded after 57% of all meals (breakfast 60%, lunch 57.5%, dinner 55.2%). The CGMS was generally well tolerated, but 52% of patients could not be studied for the full 12 days of monitoring. Thus hypoglycemia and excessive postprandial glycemic excursions are common in well-controlled patients with type 2 diabetes treated with a sulfonylurea with or without metformin. The CGMS is a useful research and clinical tool to assess glycemia in patients with type 2 diabetes but is not tolerated by all subjects.
Sydney Diabetes, Department of Diabetes, Endocrinology, and Metabolism, Royal North Shore Hospital, St. Leonards, Sydney, Australia. lhay@doh.health.nsw.gov.au
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Hay
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Wilmshurst
Gregory
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Fulcher
D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000379:methods*; D001794:Blood Pressure; D002940:Circadian Rhythm; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology; D004435:Eating / Q000502:physiology; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006943:Hyperglycemia / Q000453:epidemiology*; D007003:Hypoglycemia / Q000453:epidemiology*; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods*; D013453:Sulfonylurea Compounds / Q000627:therapeutic use
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D013453:Sulfonylurea Compounds