Intensive Diabetes Therapy and Glomerular Filtration Rate in Type 1 Diabetes
What is the impact of intensive diabetes therapy on the long-term risk of an impaired glomerular filtration rate (GFR) in patients with type 1 diabetes?
In the Diabetes Control and Complications Trial (DCCT), 1,441 persons with type 1 diabetes were randomly assigned to 6.5 years of intensive diabetes therapy aimed at achieving near normal glucose concentrations, or to conventional diabetes therapy aimed at preventing hyperglycemic symptoms. Subsequently, 1,375 participants were followed in the observational Epidemiology of Diabetes Interventions and Complications (EDIC) study. Serum creatinine levels were measured annually throughout the course of the two studies. The GFR was estimated with the use of the Chronic Kidney Disease Epidemiology Collaboration formula. The investigators analyzed data from the two studies to determine the long-term effects of intensive diabetes therapy on the risk of impairment of the GFR, which was defined as an incident estimated GFR of <60 ml/min/1.73 m2 of body-surface area at two consecutive study visits.
Over a median follow-up period of 22 years in the combined studies, impairment of the GFR developed in 24 participants assigned to intensive therapy and in 46 assigned to conventional therapy (risk reduction with intensive therapy, 50%; 95% confidence interval, 18-69; p = 0.006). Among these participants, end-stage renal disease developed in eight participants in the intensive-therapy group and in 16 in the conventional therapy group. As compared with conventional therapy, intensive therapy was associated with a reduction in the mean estimated GFR of 1.7 ml/min/1.73 m2 during the DCCT study, but during the EDIC study was associated with a slower rate of reduction in the GFR and an increase in the mean estimated GFR of 2.5 ml/min/1.73 m2 (p < 0.001 for both comparisons). The beneficial effect of intensive therapy on the risk of an impaired GFR was fully attenuated after adjustment for glycated hemoglobin levels or albumin excretion rates.
The authors concluded that intensive diabetes therapy early in the course of type 1 diabetes was associated with a reduction in the long-term risk of an impaired GFR.
This study suggests that the long-term risk of an impaired GFR was significantly lower among persons treated early in the course of type 1 diabetes with intensive diabetes therapy than among those treated with conventional diabetes therapy. These data provide strong evidence that impairment of the GFR may be prevented in patients with type 1 diabetes with intensive therapy, and reinforce the importance of early glycemic control. It should be noted that the beneficial effects of intensive diabetes therapy on the risk of an impaired GFR may not necessarily be applicable to patients with type 2 diabetes, and may cause potential harm.
Keywords: Hemoglobin A, Renal Insufficiency, Diabetes Complications, Follow-Up Studies, Risk Reduction Behavior, Blood Glucose, Cardiology, Cardiovascular Diseases, Glomerular Filtration Rate, Diabetic Nephropathies, Creatinine, Diabetes Mellitus
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