The classification of hospitalized patients with hyperglycemia and its implication on outcome: results from a prospective observational study in Internal Medicine.

The relevance of classifying hyperglycemic hospitalized subjects (HS) as known diabetes (D), newly discovered diabetes (ND), and stress hyperglycemia (SH) is unclear. The aim of this study was to determine the prevalence, in-hospital mortality, and length of stay (LOS) of three different phenotypes of HS. Fasting glucose ≥126 mg/dL (7 mmol/L) or random blood glucose ≥200 mg/dL (11.1 mmol/L) defined HS who were categorized into three groups: D; ND (no history of diabetes and HbA1c ≥48 mmol/mol); SH (no history of diabetes and HbA1c <48 mmol/mol). The end points of the study were in-hospital mortality and LOS. Of 1447 consecutive enrolled subjects, the prevalence of HS was 28.6 % (415/1447), of these 71.6 % had D, 21.2 % SH, and 7.2 % ND, respectively. In-hospital death was 3.9 % in normoglycemic and 6.0 % in hyperglycemic subjects. Individuals with SH had an increased risk of in-hospital death (7.9 %) (HR 2.17, 95 % CI 1.18-4.9; p = 0.039), while this was not observed for D and ND patients. The mean LOS was greater in ND and SH subjects. Hyperglycemia is common, and is associated with an increased risk of in-hospital mortality and extension of hospital stay. HbA1c along with clinical history is a useful tool to identify subgroups of hyperglycemic hospitalized subjects. Individuals with SH have a longer LOS, and a double risk of in-hospital mortality. Additionally, identifying previously unknown diabetes represents a remarkable opportunity for prevention of diabetes-related acute and chronic complications.