There was as much as a 23% difference in insulin levels and as much as a 62% variation in blood glucose control among diabetes patients who shook and didn’t shake their NPH insulin pens before injecting, according to a study. Researchers found patients who didn’t shake the pens before injecting had lower insulin levels if they injected the needle flat or pointing up, and higher insulin levels if the needle was facing down. Compared with resuspended NPH insulin, lack of resuspension profoundly alters PK/PD and may contribute to day-to-day glycemic variability of type 1 diabetes. — Published online before print September 10, 2015, doi: 10.2337/dc15-0801 Diabetes Care September 10, 2015