Search

This review discusses the evidence on diabetic retinopathy (DR) in patients with diabetic foot ulceration (DFU). A systematic literature review was performed on PubMed, Medline, Springer Nature, and Scopus, following the PRISMA guidelines, using the following terms, individually or in combination: “diabetic foot ulcer” OR “diabetic foot syndrome” OR “DFU” and “diabetic retinopathy.” The initial search yielded 648 articles published between 1975 and 2020. After applying exclusion and inclusion criteria, a total of 9 articles were analyzed, assessing the correlations between DR and DFU. In all cases, DR and especially proliferative diabetic retinopathy were significantly higher in the presence of DFU, though the frequency of DR showed large variability (22.5% to 95.6%). There was a significant correlation between advanced stages of DFU and increased frequency of DR and proliferative diabetic retinopathy. On the other hand, there is a risk of accelerated progression of DR in nonhealing DFUs, possibly related to chronic inflammation and associated infection. Hence, patients with DFUs should be monitored by an ophthalmologist, and those with DR should be promptly referred to a specialized diabetic foot clinic.

Diabetic retinopathy (DR) is a microvascular disorder occurring due to the long-term effects of diabetes, leading to vision-threatening damage to the retina. The human body has an elaborate system for managing and regulating the number of key trace metals circulating in the blood and stored cells. Inadequate zinc (Zn) and concurrent excess of copper (Cu) levels are associated with an increased level of oxidative stress, which may aggravate the microvascular lesions in diabetes mellitus. Several studies have revealed a significantly lower serum Zn concentration and increased Cu levels in DR when compared with diabetic patients without retinopathy and normal controls. These abnormalities are correlated with the duration of diabetes and higher levels of HbA1C. Multiple pathological mechanisms are proposed to explain these changes including hyperzincuria associated with polyuria, glycosuria, and proteinuria in diabetic patients, as well as impaired absorption of Zn at the gastrointestinal level. Increased levels of free Cu ions may be attributed to glycation and the release of Cu ions from the Cu-binding sites of proteins. Zn supplements and selective Cu chelators may be useful to alleviate oxidative stress and prevent DR progression.

Bariatric surgery is an emerging therapeutic approach for obese type 2 diabetes mellitus (T2DM) patients, with proven benefits for achieving target glucose control and even remission of diabetes. However, the effect of bariatric surgery upon diabetic retinopathy is still a subject of debate as some studies show a positive effect while others raise concerns about potential early worsening effects. We performed a systematic review, on PubMed, Science Direct, and Web of Science databases regarding the onset and progression of diabetic retinopathy in obese T2DM patients who underwent weight-loss surgical procedures. A total of 6375 T2DM patients were analyzed. Most cases remained stable after bariatric surgery (89.6%). New onset of diabetic retinopathy (DR) was documented in 290 out of 5972 patients (4.8%). In cases with DR at baseline, progression was documented in 50 out of 403 (12.4%) and regression in 90 (22.3%). Preoperative careful preparation of hemoglobin A1c (HbA1c), blood pressure, and lipidemia should be provided to minimize the expectation of DR worsening. Ophthalmologic follow-up should be continued regularly in the postoperative period even in the case of diabetic remission. Further randomized trials are needed to better understand the organ-specific risk factors for progression and provide personalized counseling for T2DM patients planned for bariatric surgery.