Management of Hyperglycemia in the Critically Ill Patients
Leslie J. Domalik
David M. Harlan
I. GENERAL PRINCIPLES
A. Hyperglycemia in intensive care unit (ICU) patients is common due to the following:
1. Preexisting diabetes.
2. Undiagnosed diabetes.
3. Stress hyperglycemia.
4. Medications—for example, glucocorticoids, catecholamines.
5. Nutritional support—for example, TPN, continuous enteral tube feeding.
B. Associated problems.
1. Electrolyte disturbances.
2. Impaired immunity.
3. Endothelial dysfunction.
4. Poor wound healing.
5. Increased in-hospital mortality.
6. Congestive heart failure following acute myocardial infarction.
7. Ketoacidosis and hyperosmolar coma in patients with preexisting or undiagnosed diabetes.
II. PATHOPHYSIOLOGY
A. Normal glycemia.
1. Tightly regulated between 70 and 120 mg/dL, depending mostly on appropriate circulating insulin concentrations to regulate glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis.
2. ICU hyperglycemia management achieved by consistent and appropriate “insulinization” at all times.
B. Diabetes classification system.
1. Type 1 diabetes (T1D)—Formerly designated insulin-dependent, ketosis-prone, or juvenile diabetes.
a. Caused by autoimmune destruction of insulin-producing pancreatic β-cells producing near-absolute insulin deficiency.
b. Patients require exogenous insulin for survival. Discontinuing insulin therapy, even for brief intervals, leads to serious metabolic complications.
2. Type 2 diabetes (T2D)—Formerly designated non-insulin-dependent or adult-onset diabetes.
a. Caused by relative (not absolute) insulin deficiency due to defects in both insulin action and insulin secretion.
b. While T2D can typically be treated with diet, oral agents, non-insulin-injectable agents, or insulin, insulin is the most appropriate treatment during acute illness.
3. Gestational diabetes.
4. Other specific types (e.g., pancreatectomy, genetic β-cell defects, defective insulin action).
5. Drug- or chemical-induced (e.g., catecholamines, glucocorticoids).
III. DIAGNOSIS
A. Hyperglycemia is defined as a fasting blood glucose above 126 mg/dL, or any random blood glucose >200 mg/dL.
B. Treatment is recommended for blood glucose persistently above 140 to 180 mg/dL.
C. Assess severity.
1. Is ketoacidosis present?
a. Based upon history, physical findings, and laboratory results (anion gap acidosis and ketonuria or ketonemia).
b. For management, see Chapter 83.
2. Is hyperosmolarity present?
a. Based upon extreme hyperglycemia and hyperosmolarity with severe dehydration and obtundation.
b. For management, see Chapter 83.
