A Look at Old and New Insulin Formations

When choosing an insulin formulation, factors like duration of action, potency, species-source, convenience and price should be considered. Another important factor that had not received much consideration is day-to-day variability in insulin action. While onset of action, duration of action and overall time-action profile are important when attempting to mimic physiological needs, minimizing day-to-day variability is critical is for minimizing the risk of hypoglycemia while still maintaining acceptable glycemic control throughout the day. With most formulations, a peak insulin action occurs after injection and that peak should coincide with postprandial glucose absorption. Post-peak levels should meet the basal insulin requirements (fasting requirements) but should not exceed them.1 However, achieving complete congruity between exogenous insulin action and endogenous insulin requirements during these 2 different phases is challenging at best, even if assuming complete consistency between meals, post-meal activity levels, stress, etc. Thus, to avoid hypoglycemia with a practical twice-daily insulin therapy and relatively infrequent monitoring, there has to be a tradeoff. In veterinary medicine this tradeoff is typically loose glycemic control with blood glucose concentrations ranging between 100 – 300 mg/dL and some residual glycosuria and incomplete reduction of clinical signs. In people, because of the critical importance of tight glycemic control, the tradeoff is often a combination of more intensive blood glucose monitoring with a more intensive treatment protocol that combines ultra-short acting formulations with long-acting ones.2