Abstract
Intensive glucose therapy can protect the retina of individuals with diabetes, but it is unknown if it provides the same protection to patients with different severity of diabetic retinopathy (DR). We finally included DR-related studies involving intensive glucose control with large sample size and long follow-up time, including five large and high-quality randomized clinical trials (RCTs): DCCT, UKPDS, ACCORD, AdRem, and VADT. With DCCT as a reference, we supposed a DR severity threshold that is verified by other RCTs then. We found that individuals who have DR lesions that are equivalent to or less severe than moderate NPDR achieve benefits for the retina by intensive glycemic control. However, these are realized only if the HbA1c in type 1 or type 2 diabetic patients is reduced at least by 0.8% versus the control group or it is reduced to <7% and >3 years of intensive glucose control is required. If the severity of DR lesions is worse than moderate NPDR, intensive glycemic control may not bring benefits.
Highlights
Diabetic retinopathy (DR) is a progressive disease that can be divided into two stages: the earlier stage is referred to as “nonproliferative diabetic retinopathy” (NPDR) and the later stage as “proliferative diabetic retinopathy” (PDR)
The current evidence suggests that intensive glycemic control can reduce the incidence of diabetic retinopathy and delay the progression of retinopathy in patients with type 1 or type 2 diabetes in the Diabetes Control and Complications Trials (DCCT) [3], its follow-up study [7], and United Kingdom Prospective Diabetes Study (UKPDS) [4], but there is few focused on whether disparate effects exist in individuals with different DR conditions
The results suggested that intensive glycemic control slowed the progression of DR, and it is consistent with intensive blood glucose control having a beneficial effect on individuals with diabetes when their severity of DR does not exceed the moderate NPDR level defined by the International Clinical DR Disease Severity Scale
Summary
Diabetic retinopathy (DR) is a progressive disease that can be divided into two stages: the earlier stage is referred to as “nonproliferative diabetic retinopathy” (NPDR) and the later stage as “proliferative diabetic retinopathy” (PDR). Studies of intensive glycemic control in patients with newly diagnosed type 1 diabetes and type 2 diabetes, including the Diabetes Control and Complications Trials (DCCT) [3] and the United Kingdom Prospective Diabetes Study (UKPDS), and their follow-up studies [4, 5], showed a legacy effect of intensive glucose control in terms of macrovascular protection in those patients without established atherosclerotic cardiovascular disease (ASCVD). The current evidence suggests that intensive glycemic control can reduce the incidence of diabetic retinopathy and delay the progression of retinopathy in patients with type 1 or type 2 diabetes in the DCCT [3], its follow-up study [7], and UKPDS [4], but there is few focused on whether disparate effects exist in individuals with different DR conditions
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