How to manage hyperglycemia (elevation of blood sugar) in patients undergoing chemotherapy?

Management of Hyperglycemia in Patients Undergoing Chemotherapy

Patients undergoing chemotherapy should have regular blood glucose monitoring with a target range of 7.8-10.0 mmol/L (140-180 mg/dL), and treatment should be initiated with insulin therapy for most cases of chemotherapy-induced hyperglycemia. 1

Causes of Hyperglycemia During Chemotherapy

• Corticosteroids (commonly used as antiemetics or part of chemotherapy regimens) are the most frequent cause of hyperglycemia during cancer treatment, affecting 20-50% of patients 2
• Corticosteroids cause hyperglycemia through multiple mechanisms: deterioration of insulin secretion by pancreatic beta cells, increased insulin resistance in peripheral tissues, and enhanced hepatic gluconeogenesis 3
• Immune checkpoint inhibitors can cause checkpoint inhibitor-associated diabetes mellitus (CIADM), which presents similarly to type 1 diabetes with autoimmune destruction of beta cells 4
• Certain cancers themselves can cause hyperglycemia, particularly pancreatic adenocarcinoma and neuroendocrine tumors like glucagonomas 4
• All patients receiving chemotherapy for early-stage breast cancer with dexamethasone experience some degree of hyperglycemia, with severity varying by baseline glycemic status 5

Monitoring Recommendations

• All patients receiving continuous oral corticosteroids as part of chemotherapy should have blood glucose monitoring 2
• For patients without known diabetes:
  • Check random blood glucose at admission and if >140 mg/dL (7.8 mmol/L), initiate regular monitoring 1
  • For patients on glucocorticoids, monitor blood glucose levels regularly regardless of diabetes status 1
• For patients with pre-existing diabetes:
  • Monitor blood glucose 4 times daily (fasting and 2 hours postmeals) when readings are out of range or when diabetogenic medications like corticosteroids are introduced 1
  • Continue this frequency when significant changes to renal function or oral intake occur 1
• Consider continuous glucose monitoring for stable patients who are familiar with the technology 1

Treatment Approach

For Corticosteroid-Induced Hyperglycemia

• For patients without pre-existing diabetes:

  • If hyperglycemia is mild to moderate, consider NPH insulin once daily in the morning (for morning steroid doses) 1
  • Initial dose: 0.1-0.3 units/kg/day based on steroid dose and oral intake 1

• For patients with pre-existing diabetes:

  • Add NPH insulin to the usual insulin regimen, with doses determined according to steroid dose and oral intake 1
  • For dexamethasone-induced hyperglycemia, consider NPH insulin twice daily (2/3 of total daily dose in morning, 1/3 in early evening) at a total dose of 0.3 units/kg/day 1
  • Adjust insulin requirements promptly when dexamethasone is discontinued as needs can decline rapidly 1

• For severe hyperglycemia (persistent readings >20 mmol/L or "HI" on meter):

  • Refer to hospital for assessment and treatment due to risk of hyperosmolar hyperglycemic state 1

For Checkpoint Inhibitor-Associated Diabetes Mellitus (CIADM)

• Test for capillary ketones in patients suspected to have CIADM 1
• If ketones are elevated or serum bicarbonate is <16 mmol/L without alternative cause, refer to hospital for workup of potential diabetic ketoacidosis 1
• Patients with CIADM require lifelong insulin therapy due to absolute beta cell failure 1

For Severely Uncontrolled Hyperglycemia

• For severely uncontrolled diabetes with catabolism (fasting glucose >250 mg/dL, random glucose consistently >300 mg/dL, A1C >10%, or presence of ketonuria):
  • Insulin therapy combined with lifestyle intervention is the treatment of choice 1
  • After symptoms are relieved and glucose levels decrease, oral agents can be added and insulin may be withdrawn if appropriate 1

Insulin Regimen Selection

• For most hospitalized patients with hyperglycemia:

  • Use a basal-bolus insulin regimen (basal, prandial, and correction insulin) rather than sliding scale insulin alone 1
  • Target blood glucose range: 7.8-10.0 mmol/L (140-180 mg/dL) 1

• For patients receiving enteral nutrition:

  • Use basal insulin (isophane insulin every 8h, detemir every 12h, or glargine every 24h) along with short-acting insulin every 4-6h 1
  • If tube feeding is interrupted, start intravenous 10% dextrose infusion at 50 mL/h 1

• For rapid-acting insulin administration:

  • Inject subcutaneously within 5-10 minutes before meals 6
  • Rotate injection sites to reduce risk of lipodystrophy 6
  • Individualize dosage based on metabolic needs, blood glucose monitoring results, and glycemic control goals 6

Special Considerations

• Patients with pre-existing diabetes and blood glucose persistently ≥15 mmol/L or HbA1c ≥9% will often require insulin initiation 1
• Avoid sulfonylureas in patients on dexamethasone due to risk of severe hyperglycemia 1
• Metformin should be withheld on days of chemotherapy administration if there are concerns about renal function or risk of dehydration 1
• SGLT2 inhibitors should be avoided in hospitalized patients receiving chemotherapy 1

Post-Chemotherapy Follow-up

• Schedule outpatient follow-up with primary care provider, endocrinologist, or diabetes educator within 1 month of discharge 1
• For patients with poorly controlled hyperglycemia, an earlier appointment (1-2 weeks) is preferred 1
• Return to home medication regimens from the day prior to discharge to the day after discharge 1
• Consider changes to outpatient regimens based on HbA1c and blood glucose control during hospitalization 1

Hypoglycemia Management

• Define moderate hypoglycemia as blood glucose <70 mg/dL and severe hypoglycemia as <54 mg/dL 1
• Treat with oral carbohydrates or glucose for conscious patients, or intravenous glucose for patients taking nothing by mouth 1
• Review and potentially modify treatment regimens after hypoglycemic episodes 1