Glucose Testing and Management in Diabetic Patients

Introduction to Glucose Testing

The American Diabetes Association recommends self-monitoring of blood glucose (BGM) for day-to-day management combined with regular HbA1c testing every 3 months to assess long-term glycemic control 1
Venous plasma is recommended for diagnosis, while capillary blood (fingerstick) is appropriate for routine monitoring 1

The American Diabetes Association recommends HbA1c testing every 3 months for patients not meeting glycemic targets or with therapy changes; twice yearly for patients with stable glycemic control 2
General target HbA1c value is <7% for most adults, with stricter targets for younger patients and less strict targets for older adults 2
Target blood glucose values: preprandial glucose of 80-130 mg/dL and postprandial glucose <180 mg/dL 3, 4, 5
Stricter targets (HbA1c 6.5% or <7%) may be appropriate for younger patients, short duration of diabetes, no significant cardiovascular disease, and longer life expectancy, as long as it can be achieved without significant hypoglycemia or excessive therapeutic burden 6, 7, 5
Less strict targets (HbA1c up to 8%) may be appropriate for older adults (≥65 years), history of severe or frequent hypoglycemia, advanced complications, and limited life expectancy, with severe or frequent hypoglycemia being an absolute indication to modify treatment regimens 6, 7, 5, 8

Enzymatic methods, such as hexokinase or glucose oxidase, are the most common laboratory methods used (>99% of laboratories) 1
Citrate-containing tubes (citric acid, sodium citrate, EDTA) are recommended to prevent glycolysis and ensure accurate results 1
Laboratory methods should aim for imprecision ≤2.2% CV with 0% bias to minimize misclassification of patients 1

Meters should report glucose concentrations in plasma equivalent values 1
Regular evaluation of monitoring technique and use of calibration/control solutions are essential for quality control 9
Portable glucose meters should NOT be used for diagnosing diabetes 1
The FDA standards require home-use glucose monitors to have 95% of readings within 15% of actual blood glucose values 1
Factors affecting accuracy include oxygen levels, medications, and environmental factors, which can impact glucose oxidase-based meters 10

Newer factory-calibrated CGMs eliminate the need for fingerstick calibration and have minimal lag time (4-12 minutes) between blood and interstitial glucose 11
CGM technology may be particularly valuable for patients with advanced chronic kidney disease who have a higher risk for severe hypoglycemia 11
Available CGM options include Abbott FreeStyle Libre, Dexcom G6, and Medtronic systems, as listed by the American Diabetes Association 12

Professional-use meters with higher accuracy standards should be used in hospitals and acute care facilities 1
Only meters specifically intended for use in newborns should be used due to hematocrit considerations 1
Patients with advanced CKD have a higher risk for severe hypoglycemia and may benefit from CGM technology 11
Critically ill patients: initiate insulin therapy when glucose exceeds 180 mg/dL and maintain a range of 140-180 mg/dL 13, 14, 15
Non-critically ill patients: preprandial glucose <140 mg/dL and random glucose <180 mg/dL, with stricter targets (110-140 mg/dL) possibly appropriate for selected patients if achievable without significant hypoglycemia 13, 14, 15, 12

Hypoglycemia is classified into three levels: Level 1 (glucose <70 mg/dL and ≥54 mg/dL), Level 2 (glucose <54 mg/dL), and Level 3 (severe event characterized by mental and/or physical impairment requiring assistance) 3, 16
Treatment involves administering 15-20g of glucose for conscious individuals with glucose <70 mg/dL, reevaluating after 15 minutes, and repeating treatment if hypoglycemia persists, followed by consuming a meal or snack to prevent recurrence 3
Treatment of hypoglycemia includes oral carbohydrates for conscious patients, IV glucose for NPO patients, and glucagon (intranasal or subcutaneous) for patients without IV access 16
Prevention of hypoglycemia involves reviewing and modifying regimens after hypoglycemic episodes and reducing medications with high hypoglycemia risk (sulfonylureas, certain insulins) 16

Using portable meters for diagnosis rather than monitoring can lead to inaccurate results 1
Not accounting for the difference between whole blood and plasma glucose values (plasma values are approximately 11% higher) can lead to inaccurate results 1
Using counterfeit test strips can lead to inaccurate results, as warned by the American College of Physicians 10
Not using results to guide therapy can lead to suboptimal glycemic control, as reported by the American Association of Clinical Endocrinologists 10

The DCCT study demonstrated that intensive glucose control in patients with type 1 diabetes resulted in a 60% reduction in the risk of retinopathy, nephropathy, and neuropathy 17
The UKPDS study showed a 25% reduction in the overall rate of microvascular complications in patients with type 2 diabetes 17
The American Diabetes Association recommends a basal-bolus regimen for hospitalized patients rather than sliding scale insulin alone 12
Continuous insulin infusion is preferred for ICU patients with hyperglycemia, patients with hyperglycemic crises, and patients with severe steroid-induced hyperglycemia 12