Infection rates in patients with diabetes mellitus (DM) increase among those diagnosed with type 1 diabetes (T1D) as well as those with worsening glycemic control, according to a study published in Diabetes Care.

Researchers utilized the Clinical Practice Research Datalink (CPRD) to conduct a retrospective matched cohort study of patients aged 40 to 89 years diagnosed with DM. Patients were matched by age and sex to controls. Diabetes diagnosis was classified as T1D, T2D, or type uncertain.

Glycated hemoglobin (HbA1c) measurements for all patients over a 2-year period were averaged; after exclusion criteria were applied, 78,964 patients in the T2D group, 4496 in the T1D group, and 1852 with type uncertain were matched with 153,341 controls. All patients were followed until the earliest date of death, deregistration from practice or practice deregistration from the CPRD, or December 31, 2015. Mean follow-up was 4.2 years; HbA1c measurements were excluded if they fell within 2 weeks of the baseline assessment period.

Infection was identified from primary care, hospital, and death records and estimated across 18 categories; these were then grouped into 3 main subcategories: 1) any infection that resulted in a prescription for an antibiotic, antifungal, or antiviral drug within 2 weeks of the initial diagnosis; 2) any infection leading to a hospital admission; or 3) any infection that resulted in patient death.

The average HbA1c for patients with T1D was approximately 1% higher than for patients with T2D (8.3% vs 7.4%); patients with unknown DM had levels similar to patients with T1D (8.3%). Increasing levels of HbA1c were associated with younger age, longer duration of DM, deprivation (defined as unmet needs caused by a lack of resources), and obesity.

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Rates of infection increased among patients with DM as well as with increasing HbA1c. Associations between infection-related hospitalizations and DM were more significant for patients with T1D (incident rate ratio [IRR], 3.34) than for those with T2D (IRR, 1.70), and patients with DM with both good (mean HbA1c, 6%-7%) and poor HbA1c (≥11%) control were at increased risk for hospitalization compared with patients without DM (IRR 1.41 and 4.70, respectively).

Attributable risk fractions (AF%) were estimated for all 3 groups, with the largest AF% estimate for bone and joint infections (46.0%) in patients with poor glycemic control. Other large AF% estimates were found for endocarditis (26.2%), tuberculosis (23.7%), sepsis (20.8%), pneumonia (15.3%), skin infections (cellulitis 14.0%, other 12.1%), and candidiasis (16.5%). Overall, 15.7% of infection-related deaths, 16.5% of infection-related hospitalizations, and 6.8% of infections requiring a prescription were attributed to poor glycemic control.


Critchley JA, Carey IM, Harris T, DeWilde S, Hosking FJ, Cook DG. Glycemic control and risk of infections among people with type 1 or type 2 diabetes in a large primary care cohort study [published online August 13, 2018]. Diabetes Care. doi: 10.2337/dc18-0287