Blood Glucose Monitoring and Insulin Administration

Critical Care and Hospital Settings

The American Diabetes Association and critical care societies recommend monitoring blood glucose every 1-2 hours during the initial phase of IV insulin therapy in critically ill patients until both glucose values and insulin infusion rates achieve stability 1, 2, 3, 4
Once stability is achieved, the American College of Clinical Endocrinologists recommends extending monitoring intervals to every 4 hours for patients receiving continuous insulin infusions 1, 2
The 4-hourly monitoring frequency is associated with hypoglycemia rates exceeding 10% in many protocols, making it unsuitable during the unstable titration phase 3

The American Diabetes Association recommends checking electrolytes, renal function, venous pH, osmolality, and glucose every 2-4 hours until stable during treatment of diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar state (HHS) 5
The American Association of Clinical Endocrinologists recommends maintaining target glucose between 150-200 mg/dL for DKA and 200-250 mg/dL for HHS until resolution 5

The American Diabetes Association recommends checking blood glucose 15 minutes after treating hypoglycemia (<70 mg/dL) with 15-20g of fast-acting carbohydrate, and repeat treatment if still hypoglycemic 6, 7
For basal insulin adjustments, the Endocrine Society recommends using fasting plasma glucose values measured the following morning 8
For prandial insulin adjustments, the American Diabetes Association recommends checking 2-hour postprandial glucose after the largest meal to guide dose titration 8

The American Diabetes Association recommends increasing monitoring frequency during dose adjustments, illness, or changes in routine 8
Patients with hypoglycemia unawareness require more frequent glucose checks as they lack typical warning symptoms 7
The American Geriatrics Society recommends more conservative monitoring thresholds for sepsis, renal impairment, hepatic disease, and elderly patients 9
The American Diabetes Association recommends treating hypoglycemia immediately when blood glucose falls to 70 mg/dL (3.9 mmol/L) - this is the hypoglycemia alert value requiring therapeutic intervention 6, 7, 9
Level 2 hypoglycemia (<54 mg/dL) represents sufficiently low glucose to indicate serious, clinically important hypoglycemia 6, 7
The Endocrine Society recommends never delaying treatment of hypoglycemia to wait for scheduled monitoring times 7

The American Diabetes Association recommends checking glucose before each meal and snack, at bedtime, occasionally after meals, before exercise, when suspecting low blood glucose, and before critical tasks like driving 10
Intensive insulin regimens typically require 6-10 glucose checks daily, though individual needs vary 10
When using rapid-acting or short-acting insulin, check glucose immediately before meals 11
If oral intake is uncertain or poor, administer prandial insulin immediately after eating and adjust the dose based on actual carbohydrate consumed 12, 11
For basal insulin only, check fasting glucose the following morning to guide basal insulin dose adjustments 10

For patients eating meals, check glucose immediately before each meal 11
For patients not eating, check glucose every 4-6 hours 11, 13
The American Diabetes Association recommends checking glucose every 4-6 hours for patients who are not eating 11, 13

For enteral/parenteral nutrition, check glucose every 6 hours with correctional insulin administered subcutaneously 14
For bolus feedings, check glucose before each feeding 13
Daily adjustments based on point-of-care glucose results are critical for patients on glucocorticoid therapy 14, 13
Monitor glucose at least every 4-6 hours while patient is NPO in the perioperative period 13
Target range 80-180 mg/dL in the perioperative period 13

Do not use only sliding scale insulin without scheduled basal-bolus coverage, as this increases both hypo- and hyperglycemia risk 12, 11
Ensure glucose meters are FDA-approved with unexpired strips from licensed distributors, as accuracy varies significantly 10
Be aware that high-dose vitamin C, hypoxemia, and certain sugars (maltose, galactose, xylose) interfere with glucose meter accuracy 10