Refractive error in Chinese with type 2 diabetes and its association with glycaemic control

The aim of this study was to determine the prevalence of refractive errors and their association with glycaemic control among adults with type 2 diabetes mellitus (T2DM) in eastern China.

A community-based survey, including 913 adults with T2DM aged 30 to 89 years, was conducted. Refractive error was assessed by autorefraction, after which subjective refraction was performed. Ocular biometric parameters were measured by non-contact partial coherence laser interferometry. Myopia was defined as spherical equivalent (SE) less than -0.50 dioptres (D), high myopia as SE less than -5.00 D, hyperopia as SE greater than 0.50 D and astigmatism as cylinder less than -0.50 D.

After excluding participants who had undergone cataract surgery, 839 were included in the data analyses and 96.1 per cent were found to have refractive errors. The overall prevalences of myopia, high myopia, hyperopia and astigmatism were 28.2 per cent (95 per cent confidence interval [CI] 25.2-31.3), 6.3 per cent (95 per cent CI 4.7-8.0), 46.4 per cent (95 per cent CI 43.0-49.7) and 81.0 per cent (95 per cent CI 78.4-83.7) with no gender differences observed (all p > 0.10). In multivariate analysis, myopia was associated with decreasing age (odds ratio [OR] = 0.86, p = 0.01; per year increase), higher blood levels of haemoglobin A_1c (HbA_1c ) (OR = 1.12, p = 0.05; per unit increase), higher education levels (OR = 5.10, p < 0.001; university or college versus illiterate or primary school) and the presence of nuclear cataract (OR = 2.36, p < 0.001).

Refractive errors may be associated with glycaemic control among T2DM patients. Longitudinal analyses are warranted to examine the relationship between changes in HbA_1c and the development of refractive errors.