Glucose

Normal levels: 70 to 160mg/dL

Physiology:

The maintenance of adequate blood glucose concentrations is a function of complex regulatory mechanisms that are primarily under hormonal control.  Fasting glucose is the most useful indicator of glucose metabolism.  Metabolically stressed patients may present with hyperglycemia in the absence of diabetes.

Hyperglycemia: levels > 160 mg/dL

Causes:

Assessment:

Patients may present with the classical signs of hyperglycemia (polyuria, polydipsia and polyphagia) or they may be asymptomatic.

Labs:

Fasting glucose above 160 mg/dL.

Correction:

Administer insulin.

TPN correction:

1.  Maintain the current TPN infusion rate and begin adding regular insulin to the TPN solution in 10 unit increments until the serum glucose is maintained at or below 160 mg/dL. (NOTE: The maximum allowable insulin dosage per liter of TPN is 40 units).  Until the hyperglycemia is controlled by adding insulin to then TPN solution, simultaneously administer intravenous regular insulin. (NOTE: 1 unit of regular insulin results in approximately a 10mgldL decrease in the serum glucose.  The maximum single IV dose of regular insulin should not exceed 15 units).

If the serum glucose remains above 160 mg/dL despite the addition of a total of 40 units of regular insulin per liter of TPN and intravenous regular insulin therapy then:

2. Maintain the current TPN infusion rate but begin gradually decreasing the dextrose concentration of the TPN solution.  (NOTE: The lower limit for the final dextrose concentration is 15%.) In addition, begin adding regular insulin to the TPN solution in 10 unit increments until the serum glucose is maintained at or below 160 mg/dL or the maximum allowable insulin dosage of 40 units is reached.  Regular insulin should also be simultaneously administered intravenously as in #1 above until the hyperglycemia is controlled by adding insulin to the TPN solution.

If the serum glucose remains above 160 mg/dL despite adding 40 units regular insulin per liter of TPN solution, decreasing the final TPN dextrose concentration to 15% and administering intravenous regular insulin therapy then:

3. Restart the original TPN solution (#l above) but begin decreasing the TPN infusion rate.  Also begin insulin therapy as discussed in #2 above while simultaneously increasing the frequency of fat emulsion therapy from every Monday, Wednesday and Friday to either daily or every other day to provide adequate caloric intake.

Hypoglycemia: levels < 70 mg/dL

Causes:

Assessment:

Symptoms of hypoglycemia include sweating, hunger, anxiety, trembling, blurred vision, weakness, headache, and/or altered consciousness.

Labs:

Fasting glucose below 70 mg/dL

Correction:

Administer dextrose.

TPN correction:

If the TPN infusion administered to either an NPO patient or a patient consuming inadequate oral calories is suddenly discontinued, immediately begin an infusion of D10NS at the current TPN infusion rate per either the TPN catheter or a peripheral I.V to prevent 'rebound' hypoglycemia.