Impact of Glycemic Control on Risk of Infections in Patients With Type 2 Diabetes

A Population-Based Cohort Study

Anil Mor; Olaf M. Dekkers; Jens S. Nielsen; Henning Beck-Nielsen; Henrik T. Sørensen; Reimar W. Thomsen


Am J Epidemiol. 2017;186(2):227-236. 

In This Article

Abstract and Introduction


Infections are a major clinical challenge for type 2 diabetes patients, but little is known about the impact of glycemic control. We used Cox regression analyses to examine the association between baseline and time-varying hemoglobin A1c (HbA1c) values and development of community antiinfective-agent-treated and hospital-treated infections in 69,318 patients with type 2 diabetes diagnosed between 2000 and 2012 in Northern Denmark. Incidence rates were 394/1,000 patient-years for community-treated infections and 63/1,000 patient-years for hospital-treated infections. The adjusted hazard ratios for community-treated infection at an HbA1c level of ≥10.50%, as compared with 5.50%–<6.49%, were 0.97 (95% confidence interval (CI): 0.94, 1.00) for HbA1c measured at early baseline, 1.09 (95% CI: 1.03, 1.14) for updated mean HbA1c, 1.13 (95% CI: 1.08, 1.19) for updated time-weighted mean HbA1c, and 1.19 (95% CI: 1.14, 1.26) for the latest updated HbA1c. Corresponding estimates for hospital-treated infections were 1.08 (95% CI: 1.02, 1.14) for early baseline HbA1c, 1.55 (95% CI: 1.42, 1.71) for updated mean HbA1c, 1.58 (95% CI: 1.44, 1.72) for updated time-weighted mean HbA1c, and 1.64 (95% CI: 1.51, 1.79) for the latest updated HbA1c. Our findings provide evidence for an association between current hyperglycemia and infection risk in type 2 diabetes patients.


Infections are a major clinical challenge for persons with type 2 diabetes and a common cause of death.[1,2] Type 2 diabetes patients have a 1.5- to 3-fold increased risk of primary-care-treated infections, particularly hospital-treated infections, compared with the general population,[1–5] but the exact mechanisms linking diabetes and infections are not well understood.[6,7]

Risk of infection among type 2 diabetes patients may depend on glycemic control. Although randomized trials and observational studies have consistently shown that early intensive glycemic control reduces the risk of diabetic microvascular complications by 10%–25%,[8–12] the effect on infections has not been examined in randomized trials.[13–21] Attempts to use observational data to clarify these issues have been hampered by inconsistent results. In addition, hemoglobin A1c (HbA1c) concentration has usually been measured on a single occasion in patients with prevalent diabetes, preventing clarification of the importance of acute hyperglycemia versus longer-term hyperglycemia.[22]

The issue of whether poor glucose control in persons with type 2 diabetes is associated with an increase in community prescriptions for antiinfective agents has not been examined to date. Such data are needed to understand and potentially prevent infections. We therefore undertook a large, population-based study to assess in detail the impact of glycemic control on risk of infectious complications in persons with type 2 diabetes.