The Association Between Glycosylated Hemoglobin A1c (HbA1c) and Outcomes in the Critically Ill

Objectives: The primary objective of this study is to determine hospital mortality of all newcomers admitted to the ICU, and to compare it between patients with HbA1c <6.5% and ≥6.5%. Other outcomes that will be measured include ICU and one year mortality, ICU and hospital length of stay (LOS), days on mechanical ventilation, serious infection during hospitalization and renal failure requiring dialysis during hospitalization and at 6 months. The investigators will also determine the prevalence of pre-diabetes (HbA1c 6.0-6.4%) and diabetes (≥6.5%) in the critically ill population based on HbA1c levels and monitor glucose control and insulin requirements during the first three days of ICU admission.

Methods: This project is a prospective observational study at the McGill University Health Center adult medical and surgical ICUs. HbA1c is measured at the admission to the ICU. The data are being collected prospectively using Microsoft access data entry. The following parameters will be recorded on admission: admitting diagnosis, sex, age, height, weight, body mass index (BMI), Acute Physiology and Chronic Health Evaluation (APACHE) II score, previous diagnosis of DM, whole blood HbA1c level, blood and plasma glucose levels. With power 80%, type I error 5% and with an expected 25% mortality difference between patients with HbA1c≥6.5 and <6.5, the required sample size is 1800 patients. The data will be presented as mean ± SD unless otherwise specified and statistical significance will be set as P < 0.05. All p-values presented will be 2-tailed.

Significance: The investigators want to demonstrate that HbA1c ≥6.5 on admission to an intensive care unit is associated with increased 6 month mortality and worse outcomes. The investigators will also determine the prevalence of pre-diabetes and diabetes in the critically ill based on HbA1c.