Long acting insulin analogues versus NPH insulin (human isophane insulin) for type 2 diabetes mellitus

NPH (Neutral Protamine Hagedorn) insulin is the current standard for basal insulin in the blood glucose lowering therapy in people with type 2 diabetes mellitus. The mode of action of this insulin is highly variable, which may be the cause for the difficulties some people with diabetes have to achieve current goals for long-term metabolic control. Therefore, new insulins which are thought to show more favourable properties of action have been developed: insulin glargine and insulin detemir. Because of their theoretical advantages, it is thought that treatment with these new insulin analogues might lead to a beneficial effect, for example less hypoglycaemia or a better metabolic control, possibly resulting in higher quality of life and treatment satisfaction less late diabetic complications such as problems with eyes, kidneys or feet and myocardial infarction, stroke or death.
Although epidemiological studies indicate that high concentrations of blood glucose carry a higher risk for these late complications, evidence for a beneficial effect of glucose-lowering therapy is conflicting. Following from the different results of large clinical trials, interventions seem to carry different substance specific beneficial or adverse effects. As a consequence, conclusions on the effects of different blood glucose lowering interventions on these outcomes can not be drawn from their effect on blood glucose concentration alone.
Methodological quality of all the studies was rated low ("C"). Eight studies investigated altogether 2293 people. Trials lasted between 24 and 52 weeks. Our analysis of the currently available long-term trials comparing long acting insulin analogues with NPH insulin showed that insulin glargine and insulin detemir were almost identically effective compared to NPH insulin in long-term metabolic control (HbA1c). Fewer people experienced symptomatic overall or nocturnal hypoglycaemic episodes with treatment with either of the two analogues. No conclusive information on late complications or on possible differences in the number of fatalities exists. For insulin glargine one study found a higher rate of progression of diabetic retinopathy in patients treated with insulin glargine, while in another investigation the opposite result was found. It was thus not possible to conclude for certain whether insulin glargine treatment is safe or not. From the retrieved trials it was also not possible to draw firm conclusions on the effects of these new insulins on quality of life or their cost effectiveness. Until long-term data on benefit and risk are available, we suggest a cautious approach to treatment with insulin glargine or insulin detemir.