Effects of intensive glycemic control in ocular complications in patients with type 2 diabetes: a meta-analysis of randomized clinical trials

Abstract

Whether intensive glycemic control can reduce incidence of diabetic retinopathy or other diabetes-associated ocular complications remains undefined. In this meta-analysis, we assessed the effects of intensive versus conventional glycemic control in ocular complications in patients with type 2 diabetes. A systematic literature search of PubMed, Web of Knowledge, and Scopus (until December 12, 2013) was conducted. Randomized controlled trials which compared intensive glycemic control with conventional glycemic control in ocular events in patients with type 2 diabetes were included. Random-effects models were used to measure the pooled odds ratio (OR) with 95 % confidence interval (CI). Seven trials involving 32,523 patients were included. Intensive glycemic control reduced the risks of retinal photocoagulation or vitrectomy (OR 0.86; 95 % CI 0.75-0.98), macular edema (OR 0.65; 95 % CI 0.43-0.99), and progression of retinopathy (OR 0.69; 95 % CI 0.55-0.87). No significant risk reduction was shown in incidence of retinopathy (OR 0.67; 95 % CI 0.26-1.73), cataract surgery (OR 0.88; 95 % CI 0.76-1.03), or severe loss of vision or blindness (OR 0.99; 95 % CI 0.86-1.13). Intensive glycemic control reduces the risk of most retinopathy-related events. But no beneficial effect was shown in ocular endpoint as severe loss of vision or blindness.

A systematic review of risk factors for cataract in type 2 diabetes

“…The RCTs focused on the effects of glycaemic control, hypertension, and/or aspirin use on CS. No significant association (odds ratio [OR] and 95% confidence intervals [CI] 0.88 (0.76‐1.03) was found in a prior meta‐analysis of the effect of intensive glycaemic control on CS . As there were not sufficient other RCTs with the same risk factors (two on hypertension, one on dyslipidaemia, and one on aspirin), no updated meta‐analysis was conducted.…”

“…Two of the negative studies included participants with newly diagnosed diabetes and thus a relatively short duration of glycaemic exposure. These RCTs were included in a meta‐analysis by Zhang et al from which it was concluded that, compared with conventional diabetes treatment, intensive management did not significantly attenuate cataract development (OR 0.88 [95%CI: 0.76‐1.03]) …”

Glycemic Control for Patients With Type 2 Diabetes Mellitus: Our Evolving Faith in the Face of Evidence

“…9–14 The body of evidence, previously summarized in meta-analyses of large RCTs, appears to confirm this impression (Table S1). 15–25 This evidence has contributed to a consensus reflected in universal guideline recommendations, quality improvement efforts, and clinical decisions all promoting tight glycemic control (HbA1c <6.5 or 7.0%). 26–28 The same evidence, however, has led some critics to question this consensus.…”

Update on Diagnosis and Treatment of Diabetic Retinopathy: A Consensus Guideline of the Working Group of Ocular Health (Spanish Society of Diabetes and Spanish Vitreous and Retina Society)

“…Each 1% reduction in HbA1c reduces any endpoint related to diabetes by 21% [41]. There is level 1 evidence (grade A recommendation) for intensive glycemic control for reducing the progression of DR [42, 43]. In the DCCT study of patients with type 1 diabetes, intensive therapy to maintain normal glucose blood levels and HbA1c < 6.5% reduced the risk for the development of retinopathy by 76% and the progression of retinopathy by 54% [4].…”