Is hyperglycemia (high blood sugar) secondary to corticosteroid treatment regarded as diabetes?

Corticosteroid-Induced Hyperglycemia: A Distinct Entity from Diabetes Mellitus

Hyperglycemia secondary to corticosteroid treatment is not regarded as diabetes mellitus—it is classified as a separate, drug-induced condition that typically resolves when the corticosteroid is discontinued. 1

Classification Framework

The American Diabetes Association explicitly distinguishes corticosteroid-induced hyperglycemia from diabetes mellitus in its classification system. 1 Here's the critical distinction:

• A person who develops hyperglycemia due to large doses of exogenous steroids may become normoglycemic once the glucocorticoids are discontinued. 1
• The classification emphasizes that it is less important to label the particular type of diabetes than to understand the pathogenesis of the hyperglycemia and treat it effectively. 1
• If hyperglycemia persists after steroid discontinuation, the patient likely had underlying type 2 diabetes that was unmasked or exacerbated by the drug, rather than true steroid-induced diabetes. 1

Clinical Characteristics That Distinguish It

Corticosteroid-induced hyperglycemia has unique features that separate it from diabetes mellitus:

• The hyperglycemic effect is most pronounced 6-9 hours after steroid administration (afternoon and evening) and often normalizes overnight, even without treatment. 1, 2, 3
• The degree of hyperglycemia directly correlates with steroid dose—higher doses cause more significant elevations. 2, 3
• In studies of otherwise healthy patients on high-dose prednisone for 2-3 months, hyperglycemia normalized spontaneously in all cases after discontinuation. 4
• The effects of glucocorticoids on hyperglycemia usually remit within 48 hours of discontinuation of oral administration. 5

Incidence and Risk Profile

The scope of this problem is substantial but reversible:

• Incidence of hyperglycemia ranges from 13-27% in all patients receiving corticosteroids, with 40.6% developing diabetes criteria during high-dose therapy. 1, 4
• Among patients with pre-existing diabetes, 42-72% experience worsening hyperglycemia on corticosteroids. 1
• Of patients who developed new-onset hyperglycemia during immune checkpoint inhibitor therapy, 68-76% were associated with corticosteroid administration rather than the underlying condition. 1

Why This Distinction Matters Clinically

The reversible nature of corticosteroid-induced hyperglycemia means patients should not be permanently labeled as diabetic, which has implications for insurance, employment, and psychological burden. 1

However, there are important caveats:

• Patients who develop steroid-induced hyperglycemia may have underlying glucose intolerance that was unmasked by the drug, and they may develop true diabetes years later. 1
• The odds ratio for new-onset diabetes mellitus in patients treated with glucocorticoids ranges from 1.5 to 2.5, indicating increased long-term risk. 3
• Screening or more stringent monitoring must always be performed before starting corticosteroids, and patients should be followed after discontinuation to ensure normalization. 6

Management Approach

Despite not being classified as diabetes, corticosteroid-induced hyperglycemia requires aggressive treatment:

• For significant hyperglycemia, start NPH insulin at 0.3-0.5 units/kg/day given in the morning to match the pharmacokinetics of glucocorticoids. 2, 3
• Monitor blood glucose four times daily (fasting and 2 hours after each meal), with particular attention to afternoon readings when steroid effects peak. 2, 3
• Target blood glucose range should be 100-180 mg/dL (5.6-10.0 mmol/L). 2
• As steroid doses are reduced, insulin doses must be proportionally decreased to avoid hypoglycemia. 2

Common Pitfall to Avoid

Do not rely solely on fasting glucose to monitor steroid-induced hyperglycemia—this will miss the peak hyperglycemic effect that occurs in the afternoon and evening. 2, 3 This is the most frequent error in clinical practice, leading to underestimation of severity and delayed intervention. 2

After steroid discontinuation, reassess glucose status within 48 hours to 8 weeks to determine if hyperglycemia has resolved or if underlying diabetes exists. 4, 5