After analyzing the amount of antibiotic prescriptions Type I diabetic patients purchased in a year, a team of researchers from Finland suggests bacterial infections may pose an increased risk of severe diabetic retinopathy (DR),

The investigation, published in the British Journal of Ophthalmology, enrolled 1,043 adults with TypeIdiabetes (413 with severe DR and 630 without severe DR) from the Finnish Diabetic Nephropathy Study, a prospective follow-up investigation. The study defined DR as incident severe diabetic retinopathy identified as incident retinal laser treatment.

 The researchers used fundus photography and medical records to gather data on DR and accessed information on bacterial infections from comprehensive national registries over a 20-year period between 1995 and 2015. Additionally, the investigators determined risk factors for DR and serum bacterial lipopolysaccharide activity at baseline.

The study found individuals with incident severe DR purchased more antibiotics per follow-up year compared with individuals without severe DR (0.92 vs. 0.67).

Patients who purchased one or more antibiotics per follow-up year (n=269) had a 1.5 times higher cumulative incidence of severe DR compared with individuals with less than one purchase (n=774) per follow-up year (52% vs. 35%). Additionally, each annual antibiotic purchase increased the risk of incident severe DR by 16%.

Patients with incident severe DR also had higher mean serum bacterial lipopolysaccharide activity (0.62 vs. 0.56). Bacterial serum lipopolysaccharide activity proved to be an independent and significant risk factor for incident severe DR, even after adjusting for traditional risk factors of severe DR, the researchers noted.

Additionally, the investigators observed significant differences for all relevant risk factors for DR between the two groups. Particularly, the distribution of diabetic kidney disease was heavily skewed, as 91% of individuals without severe DR had a normal albumin excretion rate at baseline and only 2% had macroalbuminuria, while 49% of those with severe DR had a normal albumin excretion rate and up to 26% had macroalbuminuria, the researchers noted.

Gender may also play a role in the findings, since a significant difference in the distribution between the sexes was also observed: 59.3% of individuals with severe DR were males, compared with 49% in individuals without severe DR.

 “To our knowledge, this association has not been shown previously and in line with previous research demonstrates how bacterial infections associate with the development of late diabetic complications,” the researchers wrote in their paper.

Simonsen JR, Järvinen A, Hietala A, et al. Bacterial infections as novel risk factors of severe diabetic retinopathy in individuals with type 1 diabetes. British Journal of Ophthalmology. September 14, 2020. [Epub ahead of print].