Cataract in patients with diabetes mellitus—incidence rates in the UK and risk factors

Abstract

AimsTo analyze the risk of incident cataract (diagnosis or extraction) in patients with or without diabetes focusing on other comorbid conditions, antidiabetic drug use, and diabetes duration.MethodsThe study population comprised newly diagnosed diabetes patients (≥40 years) from the UK-based Clinical Practice Research Datalink (CPRD) between 2000 and 2015, and a random sample of the general population matched for age, sex, general practice, and year of diabetes diagnosis. We assessed cataract incidence rates (IRs) and performed a nested case-control analysis in the diabetic cohort to assess potential risk factors for a cataract.ResultsThere were 56,510 diabetes patients included in the study. IRs of cataract were 20.4 (95% CI 19.8–20.9) per 1000 person-years (py) in patients with diabetes and 10.8 (95% CI 10.5–11.2) per 1000 py in the general population. IRs increased considerably around the age of 80 years and with a concomitant diagnosis of macular edema. The incidence rate ratio (IRR) was highest in patients of the age group of 45–54 years. In the nested case-control study, we identified 5800 patients with cataract. Risk of cataract increased with increasing diabetes duration (adj. OR 5.14, 95% CI 4.19–6.30 diabetes for ≥10 years vs. diabetes <2 years).ConclusionsAccording to our study, diabetes is associated with an approximately two-fold increased detection rate of cataract. The risk of cataract associated with diabetes is highest at younger ages. Patients with diabetic macular edema are at an increased risk for cataract as well as patients with long-standing diabetes.

A systematic review of risk factors for cataract in type 2 diabetes

“…By contrast, blood pressure was inconsistently associated with cataract in two observational studies. Becker et al found hypertension increased, while Tung et al found diastolic blood pressure ≥ 90 mmHg (after adjusting for blood pressure lowering medication) decreased, the odds of cataract . There was no association in the other observational studies.…”

“…18,28,[31][32][33][34]36 The UKPDS and four observational studies showed a positive relationship with HbA 1c and one study showed a positive relationship with fasting blood glucose. 18,28,[32][33][34]36 Worse glycaemic control was associated with a higher likelihood of cataract in all but one study, the SN-DREAMS II, which found HbA 1c was protective against PSC cataracts (OR: 0.7 (95%CI: 0.5-0.9), P = 0.006). 31 A possible explanation for this unexpected finding may be the study methodology, in which participants with a different cataract and no cataract were compared with those with a specific cataract sub-type.…”

“…Most of the observational studies included total serum cholesterol as a candidate predictor and found no association . By contrast, dyslipidaemia was a risk factor for cataract in the study by Becker et al Serum triglycerides also significantly increased the odds of cataract in the Kinmen studies with a serum triglyceride ≥2 mmol/L at baseline associated with increased odds of AC (OR 2.19 [95% CI: 1.07‐4.45]) and PSC cataract (OR 2.35 [95%CI: 1.15‐4.79]) . This threshold is above the ADA recommended serum triglyceride target of <1.7 mmol/L for adults with diabetes…”

“…Three observational studies found a significant association between cataract and diabetes treatment. Becker et al and Klein et al showed that insulin, and Becker et al that oral agents including metformin, sulphonylureas, and thiazolidinediones, increased the risk of cataract compared with diet‐based management . By contrast, Janghorbani and Amini found that oral agents were protective but used diabetes treatment at the latest clinic visit in their analysis .…”

“…However, this study did not have a baseline ophthalmic assessment so differentiation between prevalent and incident cataract was not possible, and there were limited variables included in the regression analysis. Becker et al also found the odds of cataract to be increased if diabetes duration was ≥2 years in one of two models that focussed on the effect of medications, but their model did not adjust for glycaemic control or diabetes treatment . Janghorbani et al reported that a longer diabetes duration was protective against AC (RR 0.80 [95% CI: 0.78‐0.38]) .…”