February 12, 2018
Patients with diabetes have a twofold increased risk of developing cataracts compared with the general population. The risk is even higher among younger diabetes patients, say UK researchers in a large registry-based study.
Seeking to clarify the relationship between diabetes and cataract risk, they examined data on more than 112,000 patients and control persons. They found that the risk for cataract was more than fivefold greater among diabetes patients aged 45 to 54 years.
The research, published online in the journal Eye, also showed that among diabetes patients who had been living with the disease for more than a decade, the cataract risk was more than five times greater than that for patients diagnosed in the past 2 years.
Study coauthor Rupert Bourne, MD, Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, United Kingdom, said this study is only the second on the incidence of cataracts in the UK's diabetic patients since the 1980s.
He noted in a press release from his institution that it "further emphasizes" the importance of screening for the "early identification and treatment of diabetic eye disease to prevent sight loss."
Bourne added that the study "is an interesting example of how a very large primary care dataset of electronic patient data, in this case the Clinical Practice Research Datalink, can be used to investigate risk factors for eye disease."
Cataract Risk Increases With Duration of Diabetes
To quantify the association between diabetes and cataract risk, the researchers examined the UK Clinical Practice Research Datalink (CPRD), which contains data on 10 million people. Their analysis took into account potential confounding factors.
Patients in the study were aged 40 years or older. They were classified as having diabetes if they had received at least two prescriptions for diabetes medications from 6 months before to 1 year after they had first been diagnosed with diabetes.
These patients were matched with diabetes-free patients on the CPRD for age, sex, general practitioner, and start of follow-up. All participants were required to have at least 3 years of medical history in the database before starting follow-up.
The researchers identified 56,510 patients with a first-time diagnosis of diabetes and the same number of control persons without diabetes. The mean age of the participants was 60.1 years.
Overall, the incidence rate of cataract diagnoses and surgery cases was 20.4 per 1000 person-years among patients with diabetes, vs 10.8 per 1000 person-years in those without diabetes.
The incidence rate rose with increasing age; the highest rates seen in individuals aged 80 years and older.
The incidence rates of cataract diagnosis in diabetic patients with a diagnosis of macular edema were considerably higher than in the general diabetic population, at 59.0 per 1000 person-years.
Incidence rates of cataract diagnosis in diabetic patients with retinopathy appeared to be only slightly higher than in the overall diabetic population.
The team calculated that the incidence rate ratio (IRR) of cataracts between diabetic patients and nondiabetic individuals was 1.9 overall. It was highest in patients aged 45 to 54 years. The IRR was 4.6 for those aged 45 to 49 years and 5.8 for those aged 50 to 54 years.
The lowest IRR was in patients aged 90 years or older, at 1.6.
In a nested case-control analysis, the researchers compared 5800 cataract patients and 21,432 control persons, whose mean age was 72.1 years.
They found that diabetes duration was significantly associated with the risk for cataract, at an adjusted odds ratio (OR) of 2.05 for 5.0 to 9.9 years' duration vs <2.0 years, and 5.14 for ≥10.0 years vs <2.0 years (P < .001 for trend).
An increased risk for cataract was also seen with long-term exposure to steroids, at an OR of 1.87 for ≥30 prescriptions vs no prescriptions.
The researchers conclude: "This large observational study demonstrates that incidence rates of cataract diagnosis in patients with diabetes are higher than among diabetic-free patients, particularly at younger age.
"The overall approximately twofold increased risk of cataract diagnosis associated with diabetes increases with diabetes duration."
Bourne reiterated: "The report has shown that having diabetes doubles your risk of being diagnosed with a cataract, and that this risk is six times higher if a diabetic patient has significant diabetic retinal disease, called diabetic maculopathy."
The study was supported by an unconditional grant of Alimera Science Ltd. The authors have disclosed no relevant financial relationships.
SOURCE: February 12, 2018. Eye. Published online February 1, 2018.