CYGB and diabetes mellitus: Results of a Korean cross-sectional study based on 2123 patients with diabetes mellitus (17) showed that high HGB levels significantly reduced the risk of DR prevalence; in addition there are also scholars (18) found a significant negative association between HGB levels and the index and severity of retinal ischemia in DR; Previous studies (19) have also confirmed that anemia is an independent risk factor for DR and DN; combined with the above studies, high HGB levels have been shown to delay the development of DR and DN.