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Poor Glycemic Control Increases Infection Risk

Nov 24, 2018
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Angela Reyes, Pharm.D. Candidate, LECOM College of Pharmacy

Infection risk is high among people with diabetes, but can better glycemic management lower infection risk?

Studies have shown patients with type 1 and type 2 diabetes have higher risk of infections. A study done in January 2018 estimated that 6% of infection-related hospitalizations and 12% of infection-related deaths were linked to diabetes. In a more recent study, data was collected to determine if worsening glycemic control can also lead to more infection risk.


This study was a retrospective matched cohort study that reviewed average glycated hemoglobin (HbA1c) among 85,312 patients with diabetes from 2008-2009. Information was gathered from the Clinical Practice Research Datalink. Age range was 40-89 years old and patients were matched by age and sex to controls. Patient HbA1c measurement was averaged over two years. Groups were made up of 78,964 patients in the type 2 diabetes group, 4,496 in type 1 diabetes group, and 1,852 with an unknown type of diabetes. They were then matched with a control. Length of study followed patients until date of death or deregistration from database or Dec. 31, 2015.

Infection rates were gathered from 2010-2015 and were taken from primary care offices, hospitals, and mortality records. The infections were ultimately grouped into 3 categories: any infection that resulted in medication use (antibiotic, antifungal, or antiviral drug) within 2 weeks of the initial diagnosis, an infection that led to hospital admission, or an infection that caused patient death. A poisson regression was used to estimate incidence rate ratios using HbA1c for patients.

The results showed patients with increasing HbA1c levels had higher incidence of infection. Patients with HbA1c between 6-7% had fewer hospitalizations due to infections compared to HbA1c of greater than 11%. Patients with type 1 diabetes and poor management had even greater risk of hospitalization from infection. These patients had 1% higher infection rate than patients with type 2 diabetes. The patients with an unknown type of diabetes had rates similar to patient with type 1 diabetes. Serious infections were seen in patients with poor diabetes management. Types of infection included bone and joint, endocarditis, tuberculosis, and sepsis. Also, increases in HbA1c were seen more in younger patients, those who have had diabetes longer, obesity, and patients with lack of resources.

Infection rates are higher among the population with diabetes. This study showed increases in HbA1c can be associated with increased risk of infection. Patients with little management of blood glucose levels risk developing serious infections especially among the population with type 1. Keeping HbA1c below 7% is optimal.

Practice Pearls:

  • Risk of infections are greater among patients with type 1 and 2 diabetes.
  • Elevated HbA1c can increase risk of infections.
  • People with type 1 need even better management of HbA1c as infections were more prevalent among this group.


Julia A. Critchley, Iain M. Carey, Tess Harris, Stephen DeWilde, Fay J. Hosking, Derek G. Cook. Glycemic Control and Risk of Infections Among People With Type 1 or Type 2 Diabetes in a Large Primary Care Cohort Study. Diabetes Care. (Aug 2018), DOI: 10.2337/dc18-0287

Iain M. Carey, Julia A. Critchley, Stephen DeWilde, Tess Harris, Fay J. Hosking, Derek G. Cook. Risk of Infection in Type 1 and Type 2 Diabetes Compared With the General Population: A Matched Cohort Study. Diabetes Care (Jan 2018): DOI: 10.2337/dc17-2131

Angela Reyes, Pharm.D. Candidate, LECOM College of Pharmacy