MedWire News: Aggressive glucose lowering treatment to current target glycated hemoglobin (HbA1c) levels increases the incidence of severe hypoglycemia and fails to reduce the risk for vascular events compared with treating to more moderate targets, results of a meta-analysis indicate.
“Current guidelines recommend a target HbA1c level of 7.0% or less for most patients with diabetes,” note Meng Wei (Shanghai Jiao Tong University, China) and associates.
“Some believe that the lower the HbA1c level, the lower the risk for either microvascular or macrovascular complications,” say the authors. “However, this belief is not based on a systematic review of the available evidence.”
Accordingly, Wei and team searched various literature databases for randomized, controlled trials that compared vascular outcomes with intensive versus standard glycemic control in individuals with Type 2 diabetes.
The authors identified eight relevant studies, including the ACCORD and UKPDS trials, involving a total of over 32,000 patients.
In three studies where the intensive glycemic control target HbA1c was <7.0% compared with 7.0–8.5% in the standard therapy group, there was no difference in combined macrovascular events, cardiac events, or stroke between the two treatments, nor in the microvascular endpoints of nephropathy, retinopathy, or neuropathy. However, there was a higher rate of hypoglycemia among intensively treated than in standard therapy patients (relative risk [RR]=2.34).
Meanwhile in five studies in which target HbA1c levels ranged from 7.0% to 7.9% in intensively treated patients compared with 7.6% to 9.4% in patients receiving standard therapy, there was again no difference between groups in macrovascular events, but lower rates of nephropathy (RR=0.43), retinopathy (RR=0.68), and autonomic neuropathy (RR=0.56) were observed with intensive therapy in two, three, and one study, respectively. These reductions in microvascular events apparently occurred without any increase in hypoglycemia rate, which was found to be no different between treatment groups in three studies.
Writing in the journal Nutrition, Metabolism, and Cardiovascular Diseases, the authors say that their findings are robust, as all data came from well-designed and conducted trials.
They note, however, that the participants in the studies were relatively young, with an average age of 59 years, and almost all had had diabetes for many years.
The researchers therefore say: “It is still unclear whether the conclusions of this analysis are applicable to older people and to patients with newly diagnosed Type 2 diabetes mellitus.”
They add: “In the future, we need more large-scale studies enrolled with more older patients or patients with newly diagnosed Type 2 diabetes mellitus.”
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