Study Shows Higher Infection Risk in Patients With T1D in Primary, Secondary Care

People with type 1 diabetes (T1D) are at an increased risk of infections compared with those without T1D, and improved glycemic control may help mitigate infection risk, according to a study published in Diabetes Research and Clinical Practice.¹

While research emerging in recent decades has shown there are pathophysiological and clinical aspects that make people with diabetes more susceptible to infections, large studies have typically focused on patients with type 2 diabetes (T2D), the study authors explained. But previous research suggested that individuals with T1D are at a higher risk of being hospitalized for infections compared with both the general population and individuals with T2D.²

“The disease burden in T1D remains high as it impacts people’s quality of life, causes serious long-term complications, and bears considerable costs for individuals and health care systems,” authors of the new study wrote.¹ “There is growing awareness that the greater susceptibility to infections amongst people living with diabetes, and especially T1D, has been largely overlooked.”

The analysis aimed to characterize the risk of infections in presenting primary and secondary care among those with T1D in a large dataset, as well as the impact of glucose control based on mean levels of hemoglobin A1c (HbA_1c) and HbA_1c variability.

A total of 33,829 patients with T1D in the Clinical Practice Research Datalink (CPRD) were included in the study. The CPRD is a real-world research service that includes patient data from across the United Kingdom and is supported by the Healthcare Products Regulatory Agency and the National Institute for Health and Care Research. Patients with T1D were matched to 2 patients without diabetes based on age, sex, and ethnicity.

Infection rates were determined by primary care and linked hospitalization records from 2015 to 2019, with incidence rate ratios (IRRs) estimated to compare patients with T1D to patients without diabetes. Of the overall T1D population, 26,096 individuals had at least 3 HbA_1c measurements available between 2012 and 2014, and the mean and coefficients of variation were estimated and compared across percentiles for comparison.

The risk of infections presenting in primary care was higher among those with T1D vs the general population (IRR, 1.81: 95% CI, 1.77-1.85), as was the rate of infections presenting in hospitalizations (IRR, 3.37; 95% CI, 3.21-3.53). After adjusting for potential confounders, including socioeconomic status, smoking, BMI, and number of comorbidities, the rates of infection were still higher for patients with T1D both in the primary care (IRR, 1.64; 95% CI, 1.61-1.68) and hospital settings (IRR, 2.74; 95% CI, 2.60-2.88).

In patients aged 18-34 years, the risk of infection was significantly higher compared with 50 or older. In primary care, the risk was 27% higher in younger patients, and the risk of infection resulting in hospitalization was 69% higher in younger patients. The infection risk among non-White patients with T1D was also estimated to be 20% higher in the primary care setting.

“This finding could be explained by higher HbA_1c mean and variability amongst these sub-population groups,” the authors wrote. 

In patients with available HbA_1c data, both mean HbA_1c and HbA_1c variability were strongly associated with the risk of infection, with the highest mean levels of HbA_1c associated with the greatest risk of infections. For example, the IRR for hospitalizations among patients with a mean HbA_1c greater than 97 mmol/mol vs those with a mean HbA_1c of 53 mmol/mol or lower was 4.09 (95% CI, 3.64-4.59).

The study’s strengths included the large sample size and up to 5 years of follow-up, as well as the follow-up period ending prior to the COVID-19 pandemic, which avoided the disruptions in primary care data during the pandemic. The study is one of the largest to assess infection-related outcomes in patients with T1D, according to the authors. Limitations to the study included the primary care reporting of infections, which are often clinical rather than determined by laboratory testing, but the authors noted that infections during hospitalization showed much higher relative risks among patients with T1D vs the general population.

“Increased infection risks in T1D should be considered as a health hazard by both patients and clinicians,” the authors wrote. ”However, UK, European and US guidance place limited emphasis on infections in the context of managing T1D.”

Researchers concluded that the findings show a clinically important increase in infection risk among patients with T1D in both primary care and hospital settings and that guidelines must be developed to reflect this risk and encourage earlier treatment.

References

1. Chaudhry UAR, Carey IM, Critchley JA, et al. A matched cohort study evaluating the risks of infections in people with type 1 diabetes and their associations with glycated haemoglobin. Diabetes Res Clin Pract. Published online November 19, 2023. doi:10.1016/j.diabres.2023.111023

2. Carey IM, Critchley JA, DeWilde S, Harris T, Hosking FJ, Cook DG. Risk of infection in type 1 and type 2 diabetes compared with the general population: a matched cohort study. Diabetes Care. 2018;41(3):513-521. doi:10.2337/dc17-2131