Background: Previous studies have assessed the efficacy of basal-bolus insulin (BBI) in hospitalized patients by measuring four finger-prick blood glucose levels (BGLs) per day. The aim of this study was to investigate whether this BGL monitoring regimen provides an accurate reflection of glycemia in hospitalized patients administered BBI. We hypothesized that, as three of four readings are preprandial, finger-prick BGLs would underestimate the mean glucose concentration. Subjects and Methods: Twenty-six consecutive consenting subjects with type 1 (n=3) or type 2 (n=23) diabetes mellitus admitted to the hospital and administered insulin glargine once daily and rapid-acting insulin before meals underwent continuous glucose monitoring for up to 72 h. Finger-prick BGLs were performed before each main meal (0700, 1200, and 1700 h) and at 2100 h. Results: Mean daily glucose concentration was not significantly different when assessed by continuous glucose monitoring and finger-prick BGLs (9.6±2.4 vs. 9.6±2.7 mmol/L, P=0.84). A Bland-Altman plot revealed some variability but no bias between the two methods of measurement of glucose concentration. There were 88 postprandial hyperglycemic excursions recorded on continuous glucose monitoring; 61 (69%) were identified by finger-prick BGL monitoring. There were 10 glucose excursions <4 mmol/L during continuous glucose monitoring; only one was detected by finger-prick BGL monitoring. Conclusions: Traditional finger-prick BGL monitoring provides a reasonable approximation of mean daily glucose concentration in the majority of hospitalized patients receiving BBI but underestimates the prevalence of postprandial hyperglycemia and hypoglycemia.