This study found that the factors such as gender, behavior of chewing betel nut, diabetic duration, family history of diabetes, HbA1c, and LDL-c, were important predictors of DR in elderly patients with T2DM. The risk of DR in female patients was higher than that of men. The longer duration of diabetes was the higher risk of retinopathy would be. The risk of retinopathy of patients with diabetic family history was higher than that of patients without family history. The patients with behavior of chewing betel nut had higher risk of developing retinopathy. The patients with higher HbA1c posed higher risk of developing retinopathy. The patients with higher LDL-c were associated with higher risk of developing retinopathy.
For the gender factors, Lopez et al. (2017) determined that retinopathy in women are more common related to retinopathy in elderly patients with T2DM.23 Another retrospective study also found that women were more likely to have retinopathy than men24, the results of which matched the results of this study. The estrogen production could regulate ocular blood flow to protect the retina; and its antioxidant effects were the primary protective effect on the lens. When women aged over 50, the concentration of estrogen would decrease year by year, and gradually lost the protect function from estrogen.25−26 The average age of women in our study was over 65 years old. These could be the reasons to explain that risk of DR was higher in females.
In a recent study of relationships between diabetic duration and risk of DR in patients with T2DM, the result showed that the prevalence of retinopathy was 1.1% at the first time of diagnosis, 6.6% for diabetes duration less than 5 years, 12.0% for diabetic duration between 5 to 10 years, 24.0% for diabetic duration between 10 to 15 years, 39.9% for diabetic duration between 15 to 20 years, and 52.7% for diabetic duration over 20 years. Therefore, the prevalence of DR in patients would rise substantially when the patient’s diabetic durations were over 10 years.27 Some studies also found that the longer duration of diabetes, the higher chance of retinopathy appeared; with impact on the risk of DR.17,24,28 The result of those studies were corresponding to our study. Therefore, well controlled earlier could prevent and delay the progression of DR in patients with diabetes.
Lopez, et al., (2017) found that patients with a family history of diabetes had a higher proportion of developing DR; and the number of patients with a family history of diabetes was about 63.4%.23 The genetic inheritance and life style had a great influence on the induction of T2DM.29 Therefore, T2DM patients with family history of diabetes should definitely manage their lifestyle and control diabetes. Keeping the blood glucose level balanced was one of the most important steps that one should take. When the blood glucose level stays high consistently, it will gradually lead to the organ damage in long term.30
In terms of blood biochemical values, blood pressure and BMI, the results of this study showed that HbA1c, TG, CHOL-T and LDL-c were highly associated with the risk of DR in elderly patients with T2DM. On the other hand, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, HDL-c, eGFR and BMI were not significantly associated with the risk of DR. A study explained that the higher HbA1c increased the risk of DR, and hyperglycemia caused injury to body organs such as nerve damage (neuropathy) kidney damage (diabetic nephropathy), and even damage to the blood vessels of the retina (diabetic retinopathy), potentially leading to vision loses.31 Stratton et al., (2000) pointed out that every 1% reduction of HbA1c could decrease the incidence of cerebrovascular accidents by 12%, the incidence of heart failure by 16%, the amputation or death caused by peripheral arterial occlusive disease by 43% and reduce the small blood vessel diseases by 37%.32 One study in China also found that the higher systolic blood pressure, higher HbA1c, higher fasting plasma glucose, higher LDL-c and lower TG were important factors to increase the risk of DR. 33 However, another study in China also showed that higher systolic blood pressure, higher HbA1c, and lower body mass index were associated with the presence of DR.34 A study from South Korean also confirmed that higher HbA1c was the significant risk factor for the incidence of DR risk in patients with T2DM.28 Comparing to those results, the increased risk of DR was caused by higher HbA1c and higher LDL-c which were consistent with our study, but TG and CHOL-T were not. Thus, well control and manage for HbA1c and LDL-c should significantly decrease the chance of developing DR in diabetes or prevent from the progression of diabetic retinopathy in diabetes patients.1,14,18,35,36
Moreover, this study found that behavior of chewing betel nut was significantly associated with the development of DR in elderly patients with T2DM and was an essential predictor of DR. Some studies found that behavior of chewing betel nut was associated with the occurrence of chronic kidney disease, and increased the risk of cardiovascular disease.37,38 Others found that chewing betel nut more frequently would increase the higher blood pressure and the behavior of chewing betel nut was also associated with an increased risk of arterial stiffness. 39,40 Therefore, it is probable to suggest that behavior of chewing betel nut could effect on small vessel disease and then it would cause the increasing of DR risk; and its relation with biological mechanism is worthy of further discussion.
This study found that the demographic characteristics in high risk group of developing DR were female, family history of diabetes, behavior of chewing betel nut and longer duration of diabetes; therefore, it would be suggested that patients with these factors should always keep their HbA1c, LDL-c, TG and CHOL-T in a normal range and give up their behaviors of chewing betel nut to prevent from developing DR. Besides, integrated care focusing on more coordinated and integrated forms of care provision would play an important role in the caring of patients with diabetes mellitus. Not only the blood glucose, blood pressure and blood lipid have to be regularly controlled and managed for patient with diabetes, but related complications of diabetes should also be regularly screened. However, anyone who had diabetes mellitus was always under the risk of developing DR; and some cases of them will be diagnosed with DR after having diabetes mellitus for many years. Thus, it is important to enable the clinical care personnel to promote the regularly health examination for T2DM patients by exploring and understanding the important predictors of DR in patients with T2DM. The early intervention for vision problems is useful to prevent severe vision loss. Doctors should also allocate patients to appropriate hospitals or clinics in time, and for patients to attend to routine pupil examinations and consultations. Nurses should also implement the education of health guidelines individually upon patient’s health condition. It will be helpful to improve and enhance the self-management abilities for patients’ health as they were under the higher risk of the progression of DR.