Usage of topical insulin for the treatment of diabetic keratopathy,including corneal epithelial defects

BACKGROUND Diabetic keratopathy(DK)occurs in 46%-64%of patients with diabetes and requires serious attention.In patients with diabetes,the healing of corneal epithelial defects or ulcers takes longer than in patients without diabetes.Insulin is an effective factor in wound healing.The ability of systemic insulin to rapidly heal burn wounds has been reported for nearly a century,but only a few studies have been performed on the effects of topical insulin(TI)on the eye.Treatment with TI is effective in treating DK.AIM To review clinical and experimental animal studies providing evidence for the efficacy of TI to heal corneal wounds.METHODS National and international databases,including PubMed and Scopus,were searched using relevant keywords,and additional manual searches were conducted to assess the effectiveness of TI application on corneal wound healing.Journal articles published from January 1,2000 to December 1,2022 were examined.The relevancy of the identified citations was checked against predetermined eligibility standards,and relevant articles were extracted and reviewed.RESULTS A total of eight articles were found relevant to be discussed in this review,including four animal studies and four clinical studies.According to the studies conducted,TI is effective for corneal re-epithelialization in patients with diabetes based on corneal wound size and healing rate.CONCLUSION Available animal and clinical studies have shown that TI promotes corneal wound healing by several mechanisms.The use of TI was not associated with adverse effects in any of the published cases.Further studies are needed to enhance our knowledge and understanding of TI in the healing of DK.

A comparative study of risk factors for corneal infection in diabetic and non-diabetic patients

AIM： To compare the clinical characteristics of infectious keratopathy in type 2 diabetes mellitus（T2DM） and nondiabetes mellitus（NDM） and to investigate risk factors for infectious keratopathy in T2DM patients. METHODS： Totally 230 patients with T2DM and 168 with NDM diagnosed as infectious keratopathy were hospitalized at Qingdao Eye Hospital from 2001 to 2015. Data including sex, age, occupation, season, smoking and alcohol consumption habits, duration between onset and treatments, duration of hospitalization were collected. Initially identified indicators were analyzed with a multivariate logistic regression. Glycosylated hemoglobin A1 c（Hb A1 c） in patients with T2DM was analyzed. The infectious keratopathies in the two groups were categorized and compared.RESULTS： The diabetic group consisted of 146（63.5%） males and 84（36.5%） females. The NDM group consisted of 111（66.1%） males and 57（33.9%） females. There was no signigicantly difference in sex distribution between the two groups（P〉0.05）. There were significant differences in age, occupation of patients, season of the onset of diseases, duration between onset and treatment, and durations of hospitalization between the two groups（P〈0.05）. In most of the patients in the diabetic group, the duration between onsetand treatment was ≤3 mo, and most was ≥3 mo in the NDM group. Multivariate logistic regression analysis revealed that age and season were related to the development of corneal infection in the T2DM group（OR=1.709, 1.706）. In the T2DM group, Hb A1 c was 9.09%±2.12%. There were statistically significant differences in the incidences of bacterial keratitis and herpes simplex keratitis in the two groups（P〈0.05）, but no significant statistical difference was found between fungal keratitis and amoebic keratitis（P〉0.05）. CONCLUSION： Advanced age and the summer and winter seasons are identified as risk factors for infectious keratopathy in T2DM patients, and T2DM patients are more prone to bacterial keratitis.

Corneal alteration and pathogenesis in diabetes mellitus

The incidence of diabetes mellitus(DM) and its complications have increased considerably worldwide. Diabetic keratopathy is the major complication of the cornea characterized by delayed corneal wound healing, decreasing corneal epithelial sensitivity, and recurrent corneal ulcers. There is accumulating evidence that diabetic keratopathy is correlated with the hyperglycemic state. Different corneal components may produce different alterations under hyperglycemia. In addition, diabetic nerve alteration may become a novel biomarker of earlystage DM. Abnormalities of the corneal nerve plexus have been associated with diabetic inflammatory states. There is rapidly growing evidence based on investigations of diabetic corneal nerves through in vivo confocal microscopy. Understanding the molecular pathogenesis caused by hyperglycemia may assist in the identification of novel biomarkers, as well as therapeutic targets for early treatment. This review mainly summarizes recent findings on corneal alteration and pathogenesis in DM.