Why are oral hypoglycemic agents (OHA) held during hospitalization?

Why Oral Hypoglycemic Agents Are Held During Hospitalization

Oral hypoglycemic agents (OHAs) are typically held during hospitalization because insulin is the preferred treatment for managing hyperglycemia in hospitalized patients, offering more predictable and titratable glycemic control in the setting of variable oral intake, acute illness, and unpredictable metabolic demands. 1

Primary Reasons for Holding OHAs

Insulin Superiority in the Hospital Setting

• Insulin is the preferred treatment for hyperglycemia in hospitalized individuals because it provides precise, adjustable dosing that can be rapidly modified based on changing clinical conditions 1
• The hospital environment creates unpredictable metabolic demands that make fixed-dose oral agents less suitable for acute glycemic management 1

Safety Concerns With Specific OHA Classes

Metformin:

• Must be avoided in patients at risk for lactic acidosis, including those with sepsis, hypoxia, impaired metformin clearance (significant renal impairment with eGFR <30 mL/min per 1.73 m²), or impaired lactic acid clearance (liver failure) 1
• Should be discontinued in patients at risk for acute kidney injury, hypoxia, shock, or before iodinated contrast imaging procedures in patients with reduced eGFR (<60 mL/min per 1.73 m²) 1
• Inpatient use of metformin in acutely ill patients (such as those with COVID-19) was associated with increased incidence of lactic acidosis (adjusted hazard ratio 4.46,95% CI 1.11–18.0) 1

Sulfonylureas:

• Associated with higher rates of hypoglycemia compared to other oral agents 2
• Their long half-life creates risk for recurrent hypoglycemia, particularly problematic when patients have decreased or unpredictable oral intake 3
• Hypoglycemia occurred in 9.5% of hospitalized patients receiving antihyperglycemic agents, with sulfonylureas being a significant contributor 2

Clinical Factors That Make OHAs Problematic

Variable Oral Intake:

• Hospitalized patients frequently have decreased or interrupted oral intake due to NPO status for procedures, nausea, or acute illness 1, 3
• OHAs require consistent carbohydrate intake to prevent hypoglycemia, which cannot be guaranteed in the hospital setting 3
• 40% of hypoglycemic episodes in hospitalized patients were attributed to decreased enteral intake 2

Unpredictable Metabolic Demands:

• Acute illness, surgery, and stress alter insulin requirements in ways that fixed-dose oral agents cannot accommodate 1
• Patients undergoing procedures or surgery require more flexible glycemic management that insulin provides 1

Risk of Hypoglycemia:

• One in 25 hypoglycemic episodes in hospitalized patients is associated with an adverse event, including seizures or unresponsiveness 2
• 2% of all hypoglycemic episodes were serious, involving seizures or an unresponsive patient 2
• Less than half of hypoglycemic patients had documented euglycemia within 2 hours, indicating difficulty in managing OHA-induced hypoglycemia 2

When OHAs May Be Continued

The 2025 ADA guidelines acknowledge that in certain circumstances, it may be appropriate to continue home oral glucose-lowering medications or initiate agents such as DPP-4 inhibitors 1

Appropriate scenarios include:

• Patients with mild hyperglycemia (blood glucose <11.1 mmol/L or <200 mg/dL) who are medically stable 1
• Those with good metabolic control on oral agents at home who maintain consistent oral intake 1
• General medicine patients without critical illness who have predictable meal schedules 1

However, even when continued, metformin requires:

• Normal kidney function (eGFR >45 mL/min per 1.73 m²) 1
• Absence of risk factors for lactic acidosis (no sepsis, hypoxia, liver disease, or acute heart failure) 1
• Lactate monitoring in fragile patients 1

The Preferred Alternative: Insulin Regimens

For most hospitalized patients with diabetes, scheduled subcutaneous insulin is recommended rather than OHAs 1

Specific approaches include:

• Basal-plus regimen for patients with mild hyperglycemia, decreased oral intake, or undergoing surgery: single dose of basal insulin (0.1–0.25 U/kg per day) plus correctional insulin 1
• Basal-bolus regimen for patients with more significant hyperglycemia and consistent oral intake: basal insulin plus rapid-acting insulin before meals 1
• Avoid sliding scale insulin alone in patients with established diabetes, as it has no proven benefit and increases risk of hypoglycemia and glucose fluctuations 1, 3

Critical Pitfall to Avoid

Never hold basal insulin in patients with type 1 diabetes, even if they are NPO—policies should be in place to ensure basal insulin is continued during care transitions 1