Statistical Methods for Best and Worst Eye Measurements.

Introduction: The focus is often on the best and worst eyes to detect early predictive and non-invasive biomarkers of diabetic retinopathy. Typically, such data have been dealt with in a case-control setting, which applies two-sample tests and ignores the correlation between the fellow eyes. Practitioners are mostly unaware that such measurements hide the labels of the fellow eyes, which rules out standard tools, such as paired t or signed-rank tests. Methods: This report discusses the problems with such data on best and worst eye measurements, and illustrates alternative paired tests for equality of means or locations using a case-control dataset. Results: This report illustrates that methods which ignore the correlation between fellow eyes result in grossly conservative tests. A battery of Z-tests which consider this correlation can resolve this issue. Discussion: This finding emphasizes the importance of selecting an appropriate control group for the detection of possible markers. Further, it cites an example to show that using data from fellow eyes and adjusting for their correlation may not always be the best option, contrary to common perception.

Effects of Lunar Phases on Foot Temperature, Oxidative Stress, and Inflammation in Type 2 Diabetic Subjects.

BACKGROUND: It has been observed that the lunar phases alter the fasting plasma glucose (FPG) level in type-2 diabetic (T2DM) subjects. Diabetic peripheral neuropathy (DPN) was also reported to be associated with elevated foot temperature (FT), oxidative stress, and inflammation in T2DM subjects. OBJECTIVES: The purpose of the present study was to evaluate the changes in FT, oxidative stress, and inflammation levels and assess the relationship of FT with oxidative stress, antioxidant enzyme activity, and inflammatory markers in T2DM subjects at different lunar phases. METHODS: The plasma glucose, glycated hemoglobin, and dorsal and plantar surface temperatures of the feet by infrared dermal thermometer were measured in 88 randomly selected T2DM subjects at different lunar phases. The levels of oxidative stress and inflammation were assessed by measuring malondialdehyde (MDA), glucose 6-phosphate dehydrogenase (G6PDH), and tumor necrosis factoralpha (TNF-α). RESULTS: The FTs, MDA, and TNF-α were significantly increased, and G6PDH activity was significantly decreased in the new moon (NM) and full moon (FM) than in the third quarter (TQ) and first quarter (FQ) for both sexes. The FTs, MDA, and TNF-α levels were significantly positively correlated, whereas G6PDH activity was significantly negatively correlated with FPG at NM and FM in both sexes. The MFT was significantly positively correlated with MDA and TNF-α and significantly negatively correlated with G6PDH at NM and FM in T2DM subjects. CONCLUSION: The lunar phases showed a prominent influence on the FT, oxidative stress, and inflammatory status in T2DM subjects, which might be due to the existence of biological rhythm interaction with lunar electromagnetic radiations.

The Amelioration of Detrimental Biochemical Anomalies by Supplementing B, C, and E Vitamins in Subjects with Type 2 Diabetes Mellitus May Reduce the Rate of Development of Diabetic Retinopathy.

Excessive intracellular glucose in insulin-independent tissues including nerve, nephron, lens, and retina invites mishandling of metabolism of glucose resulting in a background of increased oxidative stress, advanced glycation end products (AGE) formation, lipid peroxidation, and failure of antioxidant defense systems in type 2 diabetes mellitus (T2DM). All these detrimental biochemical anomalies ultimately attack biological membranes and especially capillary beds of the retina, resulting in the breakdown of the inner blood-retinal barrier and the initiation of diabetic retinopathy (DR). If these disarrays are corrected to a large extent, the development of DR can be avoided or delayed. In this prospective clinical trial, 185 patients with T2DM who received B vitamins, vitamin C, and vitamin E along with antidiabetic medication for five years demonstrated a slower rate of the development of DR and reduced abnormal biochemical mediators like reactive oxygen species (ROS), malondialdehyde (MDA), AGE, and vascular endothelial growth factor (VEGF) compared to 175 T2DM individuals who were treated with only antihyperglycemic drugs.

Do different lipid components accelerate the pathogenesis and severity of Diabetic Retinopathy?

BACKGROUND: To assess the association of lipid and lipid-derived toxic molecules in pathogenesis and severity of diabetic retinopathy (DR) in type 2 diabetes mellitus (T2DM). METHODS: The present cross-sectional study included 14 healthy individuals (HC) without T2DM, 22 T2DM subjects without DR (DNR), 24 T2DM subjects with mild non-proliferative DR (MNPDR), and 24 T2DM subjects with high-risk proliferative DR (HRPDR). All subjects underwent plasma and vitreous analysis for estimation of total lipid (TL), free fatty acid (FFA), lipid peroxides (LPOs) like malondialdehyde (MDA), 4-Hydroxy-noneal (HNE), the advanced lipoxidation end product (ALE) like Hexanoyl-lysine (HLY) and vascular endothelial growth factor (VEGF) following standard spectrophotometric and enzyme-linked immunosorbent assay (ELISA) methods respectively. RESULTS: The concentration of TL, FFA, markers of lipid peroxidation and lipoxidation as well as VEGF in plasma and vitreous were found to be significantly elevated stepwise inT2DM subjects (HRPDR > MNPDR > DNR) compared to healthy controls (HC).Further, plasma conventional lipid components like total cholesterol (TCH), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG), FFA and TL showed their significant positive correlations with vitreous level of different LPOs, ALE and VEGF in the DR group. CONCLUSION: Total lipid and lipid-derived detrimental biomolecules ultimately result in increased secretion of VEGF and thus not only add as associated mediators in the pathogenesis of DR, these also accelerate the severity of microangiopathy in T2DM.

Decreased Levels of miR-126 and miR-132 in Plasma and Vitreous Humor of Non-Proliferative Diabetic Retinopathy Among Subjects with Type-2 Diabetes Mellitus.

PURPOSE: Diabetic retinopathy (DR), the leading cause of blindness among working adults, is an urgent public health problem as diabetes mellitus (DM) is increasing at an alarming rate. Hyperglycemia-induced endothelial dysfunction is the principal contributing factor leading to the development of microangiopathy. Altered levels of microRNA (miR), the negative regulator of protein-coding genes, have been observed and considered to be markers for DR. Present study aimed to find out whether miR levels in plasma could be effective biomarkers to differentiate between type 2 diabetes mellitus (T2DM) with non-proliferative retinopathy (NPDR) from T2DM with no-DR (DNR). METHODS: We recruited 50 T2DM subjects comprising 31 NPDR and 19 DNR individuals. Surrogate markers of systemic oxidative stress and vascular endothelial growth factor (VEGF) were measured in plasma. Levels of miR-126 and miR-132 were determined in plasma and vitreous fluid using real-time PCR. RESULTS: We observed that levels of miR-126 and miR-132 were decreased in NPDR subjects in comparison to DNR. Plasma levels of miRs were inversely correlated with secreted levels of VEGF and oxidative stress marker. The levels of these miRs showed discriminating ability between NPDR and DNR. CONCLUSION: Circulating miRs 126 and 132 in plasma or vitreous may serve as biomarkers for early diabetic retinopathy risk prediction, provided validated in a larger cohort and other forms of retinal vasculopathy or retinopathy in the future.

Efficacy and Cost-Effectiveness of Anti-VEGF for Treating Diabetic Retinopathy in the Indian Population.

PURPOSE: In the present study, we aimed to evaluate the efficacy, safety, and cost-effectiveness of the anti-vascular endothelial growth factor (anti-VEGF), namely ranibizumab (RBZ) or bevacizumab (BVZ), after either focal or grid or scatter laser photocoagulation, for the treatment of diabetic macular edema (DME) in the Indian population. METHODS: Retrospective data were collected in the Regional Institute of Ophthalmology, Kolkata, India between January 2018 and June 2019. Seventy-seven eyes received 3 consecutive monthly intravitreal injections of RBZ (0.5 mg) and were followed by prompt laser photocoagulation (within 7-10 days after the third injection). Similarly, 51 eyes received 3 consecutive monthly intravitreal injections of BVZ (1.25 mg), an off-label drug, and were followed by prompt laser therapy. Safety assessments of the therapy, as well as surrogate markers of biochemical derangements related to diabetic retinopathy (DR), were also investigated at the end of 12 months. RESULTS: Seventy-seven subjects who were given a treatment of RBZ+laser therapy showed average 6.87±5.53 letters gain in their best-corrected visual acuity (BCVA) score, whereas the ones treated with off-label BVZ+ laser therapy demonstrated improvement in BCVA of an average 6.82±5.76 letters in "Early Treatment Diabetic Retinopathy Study" (ETDRS) chart. The study also highlights the cost-effectiveness of both RBZ+laser and BVZ+laser therapies for the treatment of DME in DR. The results demonstrated that a subject has to pay 20.951 times more cost (in INR) for RBZ+laser therapy compared to BVZ+laser therapy, to get an almost similar outcome. CONCLUSION: BVZ is found to be the more attractive option for treating DME in DR for its cost-friendliness over RBZ in terms of BCVA outcome, as well as the safety perspectives, at least for the economically backward population in developing countries, like India.

Effects of lunar cycle on fasting plasma glucose, heart rate and blood pressure in type 2 diabetic patients.

The purpose of this study was to investigate the influence of lunar phases on fasting plasma glucose, heart rate, and blood pressure in type 2 diabetic patients. The present cross-sectional study was carried out during four phases, i.e., full moon (FM), first quarter (FQ), new moon (NM), and third quarter (TQ), of the lunar month. The study was conducted on 42 randomly selected patients (22 males and 20 females) from the Diabetes Clinic of Calcutta Medical College. Fasting plasma glucose (FPG) of each subject was determined and heart rate (HR) and blood pressure (BP) were measured at rest and during static exercise conditions, i.e., performance of a standard handgrip dynamometer test. The FPG level during the NM and FM was significantly higher (p < .001) than during the TQ and FQ for both males and females, respectively. The mean HR during static exercise during the NM and FM for both males and females was significantly higher than that during the FQ (p < .05) and TQ (p < .01). It appears from the present study that lunar phases may affect fasting plasma glucose level and cardiovascular functions of aged type 2 diabetic patients both at rest and during exercise.

Visual contrast sensitivity could be an early marker of diabetic retinopathy.

The present study aimed to explore the early predictive marker of diabetic retinopathy (DR) and to elucidate the associated demographic, metabolic, and ocular factors. We enrolled 43 type 2 diabetic subjects with mild non-proliferative retinopathy (MNPDR), 30 diabetic subjects with no retinopathy (DNR), and 35 healthy controls (HC). The study groups showed no significant alteration in central macular thickness (CMT) and visual acuity (VA). The contrast sensitivity (CS) score was found to be significantly lower among DNR and MNPDR subjects compared to HCs (p < 0.0001). Between MNPDR and DNR subjects, the CS score was significantly lower in the former (p = 0.0036). CS score discriminated DNR subjects from HC, with 74% accuracy for the optimal threshold 0.71. The associated area under the ROC curve (AUC) is 0.82 (p < 0.0001) while the discrimination rule has 66% sensitivity and 80% specificity. The CS score also discriminated MNPDR subjects from DNR with 64% accuracy for the optimal threshold 0.53. The associated AUC is 0.65 (p < 0.023) and the rule has 86% sensitivity and 33% specificity. According to best subset regression analysis, not only glycaemic parameters but also lipid parameters [low-density lipoprotein cholesterol (LDL-C) (p = 0.045) and triglycerides (TG) (p = 0.0005)] were found to be significant predictors of CS. CMT (p = 0.058) was another marginally significant predictor of CS. CS may be used as an early predictive marker for DR. So, not only hyperglycemia, but also hyperlipidemia seems to significantly affect retinal CS function in diabetes.

Biochemical scenario behind initiation of diabetic retinopathy in type 2 diabetes mellitus.

Purpose: Despite the disease having similar glycemic status and duration microangiopathy in some patients develop within few years whereas it doesn't appear as a health complication in some diabetics for a considerable period. This study is undertaken to assess the hyperglycemia-induced biochemical background behind the development of diabetic retinopathy (DR) in type 2 diabetes mellitus (DM). Methods: Following proper diagnosis, 100 patients of type 2 DM of 10-12 years duration having no DR, and 42 patients of type 2 DM of the same duration and glycemic status as the second group, with mild retinopathy were recruited in the study. Lactic acid, glutamate, malondialdehyde (MDA), nitrate, advanced glycation end-products (AGEs), peripheral blood mononuclear cell reactive oxygen species (ROS), vascular endothelial growth factor (VEGF), and its receptor 2 (VEGFR2) in these two groups were produced in an assay following standard methodology. Results: Biochemical markers of anaerobic glycolysis, lipid peroxidation, AGEs, glutamate concentration, oxidative stress, and expression of VEGF and its VEGFR2 with significantly elevated markings were found in them who developed earliest stage of DR rather than them who had not. Conclusion: Hyperglycemia-induced anomalous glucose metabolism, lipid peroxidation, advanced glycation, glutamate toxicity, and oxidative stress create a background where apoptosis of retinal capillary endothelial cells invite increased expression of VEGF and VEGFR2, these being the crucial factors behind the development of diabetic microangiopathy.

Hyperlipidemia-Mediated Increased Advanced Lipoxidation End Products Formation, an Important Factor Associated with Decreased Erythrocyte Glucose-6-Phosphate Dehydrogenase Activity in Mild Nonproliferative Diabetic Retinopathy.

OBJECTIVES: The present study aimed to evaluate the role of hyperlipidemia in increased formation of advanced lipoxidation end products (ALEs) and to evaluate whether there is any relationship between ALEs generation and erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity in cases of mild nonproliferative diabetic retinopathy (MNPDR). METHODS: In this study, we enrolled 100 patients with type 2 diabetes and MNPDR, 100 subjects with type 2 diabetes but without retinopathy (DNR) and 90 normal individuals without diabetes as healthy controls (HCs). Erythrocyte nicotinamide dinucleotide phosphate (NADPH), G6PD activity, serum total cholesterol, low- and high-density lipoprotein (LDL, HDL) and triglyceride levels were determined by photometric assay. Serum malondialdehyde (MDA) protein adduct and hexanoyl-lysine (HEL) were measured by an enzyme-linked immunosorbent assay (ELISA). RESULTS: A robust linear relationship was observed between MDA protein adduct and LDL or cholesterol or triglyceride levels, and HEL and LDL or cholesterol or triglyceride levels in subjects with MNPDR (p=0.0001). A significant inverse association was observed between erythrocyte G6PD activity and serum MDA protein adductor HEL levels in subjects with MNPDR (p=0.0001). CONCLUSIONS: Hyperlipidemia is an important factor that is associated with increased ALEs formation in persons with MNPDR. Increased ALEs generation was associated with decreased G6PD activity and low NADPH levels in cases of MNPDR, suggesting their detrimental role in the occurrence of early NPDR.