A new study published in Diabetes/Metabolism Research and Reviews investigated the association between BMI (body-mass index), length of stay (LOS), and mortality in hospitalized patients with and without diabetes mellitus (DM). This study prospectively collected data of 24,233 adult patients hospitalized between 2011 and 2013, of which 53% were males in the age-group of 65±18 years; among these 31% patients had DM. BMI was calculated according to measurement or self-report on admission, and classified as follows: underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), obese (30-34.9) and severely obese (≥35). The findings revealed that among patients with normal BMI LOS was shorter than that of underweight patients, but longer in comparison with overweight and obese patients. Following multivariate adjustment, this difference remained significant only for patients with DM. Additionally, there was a significant interaction between DM status and BMI group, in the models for in-hospital and end-of-follow-up mortality. Compared to normal BMI, in-hospital mortality risk increased by 80% and 100% for the underweight with and without DM, respectively. Whereas, for patients with and without DM, in-hospital mortality risk was 30-40% lower among overweight and obese patients; and there was no difference between severely obese and normal weight patients. Furthermore, at the end-of-follow-up, mortality risk was 1.6 and 1.7-fold higher among underweight patients with and without DM, respectively. Whereas for overweight, obese, and severely obese patients, mortality risk was decreased by 30-40% in those with DM and by 20-30% in those without DM. From the results, it was concluded that in hospitalized patients with and without DM, there was an inverse association between BMI and mortality.