Glucose control and mortality from lower respiratory tract infections in patients with diabetes: evidence from real-world data.

backgroundDiabetes mellitus increases both susceptibility to and severity of lower respiratory tract infections (LRTIs). However, the quantitative relationship between the range of glucose control and mortality from LRTIs in patients with diabetes has not been well defined. This study evaluated the association between fasting blood glucose (FBG) at the health check-up closest to the LRTI diagnosis and subsequent LRTI mortality in patients with diabetes, using data from the Korean National Health Insurance Service–National Sample Cohort (NHIS-NSC).

methodsThis study included 4,514 adults with diabetes diagnosed with pneumonia (J12–J18) or influenza (J09–J11) in the cohort between 2002 and 2019. Mortality after LRTI diagnosis was identified using claims and cause-of-death records. FBG from the health check-up closest to the LRTI diagnosis was classified into three categories (< 80, 80–130, ≥ 130 mg/dL) based on Korean Diabetes Association recommendations. Logistic regression was performed to estimate the association between FBG categories and mortality after adjustment for age, sex, smoking status, physical activity, body mass index, hypertension, income, cardiovascular disease, and duration of diabetes. Dose–response relationships in group3(FBG ≥ 130 mg/dl) were evaluated using linear and restricted cubic spline models.

resultsAmong the study population, 212 patients (4.7%) died from LRTIs. Compared with those with target-range FBG (80–130 mg/dL), patients with FBG ≥ 130 mg/dL had a significantly higher risk of mortality (adjusted odds ratio [aOR] 1.54; 95% confidence interval [CI] 1.11–2.14). This association remained robust after excluding outliers (FBG > 383 mg/dL) and in extended adjustment models. A clear dose–response relationship was observed between FBG and mortality risk. Relative to target-range FBG, mortality risk increased 1.4-fold at 160–189 mg/dL and rose sharply to 2.5-fold at ≥ 190 mg/dL.

conclusionsReal-world data showed that elevated FBG in patients with diabetes increased the risk of mortality from LRTI. This study not only demonstrates, using real-world data, the importance of adequate glycemic control in patients with diabetes, but also identifies a threshold at which mortality risk rises sharply. These findings emphasize that appropriate glycemic control may reduce infection-related mortality and should be considered a critical component of public health strategies for diabetic populations.