In-hospital screening for diabetes mellitus with HbA1c in an internal medicine department was not useful; a prospective pilot study.

Background: Screening inpatients for diabetes mellitus may be a good opportunity to detect undiagnosed cases and several studies have demonstrated the feasibility and usefulness of this practice. HbA1c has been suggested as the method of choice due to the effects of acute illness on glucose. The aim of this study was to evaluate a screening protocol based on HbA1c to identify inpatients with undiagnosed diabetes mellitus in an internal medicine department.

Methods: We conducted a prospective study of all admissions in the internal medicine department of a 412-bed community hospital in Greece during a 6-month period. Candidates for screening based on the American Diabetes Association's recommendations were screened with HbA1c. Patients with very poor health status and patients with conditions that may interfere with HbA1c measurement or interpretation were excluded.

Results: Of 463 patients (median age 74) only a small proportion (14.9%) were candidates for screening with HbA1c. Known diabetes mellitus, a low admission glucose, severe anemia or blood loss and poor health status were the most common reasons of exclusion. Among the 55 screened patients, 7 had diabetes (based on HbA1c ≥ 6.5%). However, in only 1 of them HbA1c was above target considering the patients' health status. Categorical agreement (no diabetes, prediabetes, diabetes) between morning glucose and HbA1c was low. However, the concordance between a morning glucose < 125 mg/dl and HbA1c < 6.5% was > 90%.

Conclusions: In settings similar to ours (very elderly patients, high rate of conditions that confound the use of HbA1c and high rate of patients with poor health status), untargeted screening of inpatients with HbA1c is unlikely to be cost-effective. A morning glucose during hospitalization may be a better first step for screening.