Here is a great article by Riva Greenberg. Riva is a type 1 diabetic, and she writes articles for the Huffington Post. Her article concerns glucose meter accuracy, and other factors that influence our glucose control. The meter accuracy is important but accuracy in carb counting, and the levels of absorption of the insulin are also very important. Here is a quote from Riva's article:
" .....if a meter meets the ISO standard (95 percent of the time it's within plus or minus 20 percent of a standard lab test at glucose concentrations equal to or above 75 mg/dl, and within 15 mg/dl at values less than 75 mg/dl). Comparatively, the average error in carb counting is about 20 percent and in insulin absorption about 25 percent. Hence, a lot of inaccuracy to base my dosing on. Yet, notice meter accuracy is much less impactful to my dosing accuracy. The solution, for now, is to make each of these three factors more accurate. So if we increase meter accuracy to within plus/minus 15 percent -- the new reference standard now pending FDA approval -- and I brush up on my carbohydrate counting and get a little better at calculating my insulin dose, I'll increase my chances of getting my insulin dose more accurate more of the time."
In my case the insulin absorption is a major factor. After almost 62 years of injections, and 5 years of pumping, my body is riddled with spots of scar tissue. The level of absorption is very variable because of the scar tissue. I have to change programming on my pump every time I change infusion sets. When I change sets every 3 days I never know whether my absorption will be great, mediocre or poor. It was the same with injections. Some of my scar tissue is permanent. Be sure to rotate sites to avoid scar tissue. Here is Riva's article: