oral agents are used in the ICU for glucose control given the unpredictability of the metabolism in critically ill patients.
Depending on the glucose level, insulin can be given intravenously or subcutaneously. If there is a reading above 220 mg/dL or two consecutive readings above 180 mg/dL, the intravenous route is preferred. If the glucose reading is between 160 and 179 mg/dL, subcutaneous insulin is given. The options in subcutaneous insulin include short‐acting insulin, sliding scale insulin, NPH insulin, and long‐acting insulin.
Preferred route of insulin administration
| Glucose level (mg/dL) | Route |
| 160–179 | Subcutaneous |
| 180–219 | Subcutaneous |
| >220 | Intravenous |
| Two consecutive readings of >180 | Intravenous |
Monitoring of glucose level
When on intravenous insulin, glucose is checked every hour until it remains within goal for over 4 hours, after which it can be checked every 2 hours. If there is any change in clinical condition, insulin infusion rate, or nutritional support, switching back to hourly glucose checks is advised. When on subcutaneous insulin, glucose can be checked every 2–4 hours initially, then with meals and at bedtime once glucose is within target for over four readings.
Transitioning from intravenous to subcutaneous insulin
The last 24 hour insulin requirement is calculated by multiplying the requirement in the last 6 hours of insulin infusion, dividing by 6 and multiplying by 20; this will be the total insulin given in a day.
40% of the total daily units are given as long‐acting insulin and 60% are given as short‐acting insulin three times a day.
If giving NPH insulin, the total dose is divided by 4 and given every 6 hours.
If a patient is on less than 2 units of insulin per hour while on the drip, consider starting on short‐acting insulin.
Discontinue intravenous insulin 60 minutes after giving subcutaneous insulin.
Nutrition and insulin
For PO feeds, long‐acting insulin and short‐acting insulin are preferred.
For continuous feeds, consider NPH insulin.
If feeds are held, give basal insulin and hold rapid‐acting insulin.
If continuous feeds are held, hold NPH and long‐acting insulin and give short‐acting insulin or add D10 at previous rate of feeds.
Management of complications
The commonest complication of glucose control in the ICU is hypoglycemia which is defined as blood glucose less than 80 mg/dL. The association between mortality and glucose level is 'J‐shaped' meaning that there is increased mortality at both extremes making it important to avoid hypoglycemia.
Blood glucose 90–120: hold insulin infusion and repeat blood glucose in 1 hour.
Blood glucose 71–89: hold insulin infusion and repeat glucose in 30 minutes.
Blood glucose 51–70: give 12.5 g of 50% dextrose and repeat glucose in 15 minutes.
Blood glucose <50: give 25 g of 50% dextrose then confirm reading with arterial blood if possible and repeat glucose in 15 minutes.
Treatment/management
See Figure 8.1.
Prognosis
There are clinical, animal, and in vitro studies which support a pathogenic role of acute hyperglycemia by causing immune system dysfunction, coagulation abnormalities, and increasing overall mortality.
Reading list
1 Finfer S, et al. Clinical review: consensus recommendations on measurement of blood glucose and reporting glycemic control in critically ill adults. Crit Care 2013; 17(3):229.
2 Markovitz LJ, et al. Description and evaluation of a glycemic management protocol for patients with diabetes undergoing heart surgery. Endocrine Pract 2002; 8(1):10–18.
Suggested websites
http://resources.aace.com/protocols.html
Guidelines
National society guidelines
| Title | Source | Date and weblink |
| Diabetes Care in the Hospital | American Diabetes Association | 2019 https://care.diabetesjournals.org/content/42/Supplement_1/S173 |
| Insulin Infusion Guideline | Society of Critical Care Medicine | 2012 https://journals.lww.com/ccmjournal/Fulltext/2012/12000/Guidelines |
Evidence
| Type of evidence | Title | Comment |
| Clinical trial | Normoglycemia in Intensive Care Evaluation Survival Using Glucose Algorithm Regulation [NICE‐SUGAR] trial | Significantly higher 90 day mortality in intensive glucose control group compared with moderate glucose control |
| Clinical trial | Leuven Surgical Trial | Intensive glucose control significantly reduced ICU length of stay, hospital length of stay, duration of mechanical ventilation, and acute kidney failure |
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