In critically ill diabetes patients, relative hypoglycemia (RH) (a drop in glucose ≥30% below pre-admission levels, as measured by HbA1c) was linked to higher mortality than absolute hypoglycemia. For a study, researchers sought to look into the epidemiology and outcomes of RH when combined with insulin therapy. A cohort of critically ill diabetic patients who received insulin in a tertiary hospital’s intensive care units (ICUs) was studied retrospectively. The primary outcome was 28-day mortality from insulin therapy-associated relative hypoglycemia (ITARH). ITARH was observed in 184 (42%) insulin-treated patients. ITARH was associated with higher HbA1c (8.6% vs 6.6%, P<0.001), a higher glycemic variability index (121 vs 75.1 mmol2/L2/h/week, P<0.001), and more absolute hypoglycemia (18.5% vs 3.94%, P<0.001). Its occurrence peaked about 5 hours after the start of insulin therapy. ITARH was linked to a higher risk of subsequent hypoglycemia (adjusted HR 3.5, 95% CI 1.7–6.8) but not mortality (HR 1.2, 95% CI 0.7–2.2). ITARH was common in critically ill insulin-treated diabetes patients and was associated with poorer glycemic control. Unlike other reports of RH, it was not associated with mortality, implying that the prognostic implications of RH vary depending on the context.