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The incidence type 2 diabetes is increasing world-wide. We did a Cochrane review focusing on whether intensive glycaemic control is superior to conventional glycaemic control in reducing mortality and complications in patients with type 2 diabetes (1). Cardiovascular disease is important, because it is the main cause of premature death for these patients.

Patients with type 2 diabetes develop elevated levels of plasma glucose with disturbances in carbohydrate, fat, and protein metabolism. As type 2 diabetes is a progressive disease the glucose-lowering treatment needs to be intensified in order to achieve near normal glycaemia. The first step for patients with type 2 diabetes is ‘lifestyle’ intervention, with advice to lose weight and increase physical activity. However, in order to maintain optimal glycaemic control, most patients will require additional glucose-lowering therapy. Our review assesses the effects of targeted intensive glycaemic control compared with targeted conventional glycaemic control.

We searched for randomised clinical trials comparing these two approaches in patients with type 2 diabetes, looking for published and unpublished trials in any language; and ended up with 20 included trials, that recruited almost 30,000 patients. The duration of the interventions lasted from 3 days to 12.5 years. The patients in these trials represent a very diverse part of the population with type 2 diabetes. The diagnosis of type 2 diabetes varied among the included trials, and some trials used a definition which may have led to the inclusion of participants with impaired glucose tolerance rather than type 2 diabetes.

The results of the review should be interpreted with caution. When we combined the results of the trials, we found that the treatments did not have significantly different effects on all-cause mortality or mortality from cardiovascular disease; the same was the case for several other patient important outcomes. Among the outcomes that may be favoured when targeting intensive glycaemic control are non-fatal myocardial infarction, amputation of the lower leg, and microvascular disease assessed as a composite outcome. We were not able to perform meta-analyses for either health-related quality of life or the costs of the interventions.

We used a statistical technique in the review called trial sequential analysis to examine whether the significant effect estimates in cumulative might be due to a lack of data. Trial sequential analysis does also help to estimate how many more patients needs to be randomised before firm evidence is established.

In conclusion, uncertainty remains about the effect of intensive glycaemic control versus conventional glycaemic control on cardiovascular disease and mortality in patients with type 2 diabetes. It would be preferable to have more randomised clinical trials assessing cardiovascular disease and mortality in patients with type 2 diabetes, for example younger patients without complications and older patients with complications. Future trials should adopt more uniform and rigorous standards for reporting to ease the comparisons between different glycaemic intervention targets.

  • 1
    Hemmingsen B, Lund SS, Gluud C, Vaag A, Almdal T, Hemmingsen C, Wetterslev J. Targeting intensive glycaemic control versus targeting conventional glycaemic control for type 2 diabetes mellitus. Cochrane Database of Systematic Reviews 2011, Issue 6. Art. No.: CD008143.