Mid- and high-ratio premix insulin analogues: potential treatment options for patients with type 2 diabetes in need of greater postprandial blood glucose control.

Some patients with type 2 diabetes continue to have high postprandial blood glucose levels on twice-daily regimens of 'low-ratio' premix insulin formulations (up to 30% rapid-acting, with 70% protracted insulin). These patients require intensified insulin therapy, which can be provided by a twice- or thrice-daily regimen of mid-ratio (50% rapid-acting and 50% protaminated intermediate-acting insulin - human or analogue) or high-ratio (70% rapid-acting and 30% protaminated insulin - analogue only) premix insulin. Alternatively, a third daily injection of low-ratio premix insulin can be added to the regimen, with the option of incorporating one or more injections of mid- or high-ratio premix as required, and as an alternative to basal-bolus therapy. How these mid- and high-ratio formulations differ from the low-ratio premix insulins is reviewed here, with the aim of identifying the role of these formulations in diabetes management. Glucose clamp studies have shown that premix analogues give serum insulin levels proportional to their percentage of rapid-acting uncomplexed insulin: the higher the proportion, the greater the maximum level reached. Other pharmacokinetic parameters were not always significantly different between the mid- and high-ratio formulations. In clinical trials, postprandial plasma glucose and glycated haemoglobin A1c (HbA(1c)) levels were significantly reduced with thrice-daily mid- /high-ratio premix analogue when compared with twice-daily low-ratio biphasic human insulin (BHI) 30/70 or once-daily insulin glargine. Moreover, glycaemic control with mid-/high-ratio premix analogue was found to be similar to that with a basal-bolus therapy. Mid- and high-ratio premix regimens are generally well tolerated. The frequency of minor hypoglycaemia was reportedly higher with mid- /high-ratio premix analogues than with BHI 30, but nocturnal hypoglycaemia was less frequent. Although there is little evidence that clinical outcomes with mid-ratio premix analogues are different from those with high-ratio, they are useful additions to the low-ratio formulations for the management of diabetes, and addressing postprandial hyperglycaemia in particular.