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A Review of Insulin Errors

Oct 29, 2019

This week we have a review adapted from information provided by Novo Nordisk of the most common errors with insulin which include:

  • Clinician errors
  • Self-administration errors
  • Self-monitoring errors
  • Improper insertion techniques
  • Bad drawing-up procedure
  • Insulin timing
  • Using the wrong insulin
  • Miscalculating insulin sensitivity factor
  • Using an incorrect carbohydrate ratio
  • Not checking blood glucose 2 hrs after injection


As the incidence of diabetes increases, insulin use can reasonably be expected to increase, and the mistakes will no doubt increase as well. Insulin is a very powerful medication, and some of these mistakes will require the ambulance, the hospital, or worse.


Insulin manufacturer Novo Nordisk (the source of much of this information) estimates that morbidity and mortality rates resulting from medication errors add an estimated $1,900 per patient to total U.S. health care costs. 

What kind of mistakes do we see? There are clinician errors, self-administration errors, and self-monitoring errors. Insulin is the single most frequently misprescribed medication — everything from ill-written orders, poorly labeled vials, to incorrect rates programmed into an insulin pump.

But if the doctor errs, the patient isn’t far behind. What about maintaining dose accuracy? A “grave error,” defined as a deviation of more than 15 percent above or below the intended dose, can result from confusing instructions, inadequate patient training and education, or improper equipment. In too many settings, a diabetes educator is given a desperately short time with a new patient and is expected to impart an almost impossible volume of life-and-death information in minutes. If “education is the answer,” the chaos and confusion we see in these statistics are no surprise.

Many people develop diabetes late in life, or progress to needing insulin when they are 60 or older. (Medical professionals under age 40 averaged a 5 percent error rate with their own insulin self-administration – so nobody’s perfect.) The Novo Nordisk survey suggested that up to half of all dosage errors were among the age 60 and older population (though per capita, there’s a lot more diabetes there, too). Incorrect needles (sometimes reused far past all utility) and improper insertion techniques compete with the poor drawing-up procedure to cause more errors.

To achieve maximum control over their diabetes, many people mix insulins. This works well if done correctly – but if the patients are not careful or reverse the ratio (70 of this one; 30 of that, instead of vice versa) there will be greater or lesser degrees of trouble.

What about timing? Your insulin dose needs to come at a specific time of day. If you delay it, you will be “uncovered” for the missed time – leading to higher BG readings and higher A1C’s as well. In one study, about a third of participants delayed their morning injection by one to two hours, for whatever reasons.

And, of course, there is self-monitoring. “Sliding-scale” insulin dosage, where the patient tests his/her blood glucose every few hours, then immediately varies insulin dose to best follow the fluctuations and keep test results in the “normal range,” is the ideal, but it requires frequent and accurate finger stick tests. National surveys suggest a great many people with diabetes do not self-monitor as completely as they should, and one survey stated that 1/3 of all diagnosed diabetes patients did not self-monitor at all.

Most blood glucose monitors sold in the last 10 years are accurate; but the newer meters are easier to use, more convenient to carry, and require a far smaller drop of blood than their ancestors did. If you need to meter, there’s no excuse to be lax – you’re hurting yourself.

Insulin delivery devices are getting better all the time, too. Syringe users can use the Count-A-Dose device (now offered by Medicool, of Torrance, California, and by the National Federation of the Blind Materials Center, in Baltimore, Maryland) if they have trouble drawing up. Insulin pens, all tactile, are getting easier to use, and the variety of insulins available for them is growing.

So, what’s the moral of this tale? Several: First, insulin is a powerful medication, with serious consequences if misused. Second, there are several ways people make mistakes in their insulin administration. Third, education is important; you CAN learn how to do it right. Fourth, and perhaps the best news of all, equipment is getting better, easier, and more foolproof. Newer insulins work better than the old standbys; newer blood glucose meters are easier and more convenient than their ancestors, and newer ways to administer insulin are more adaptive, better for folks with vision or movement difficulties, than the older syringes, pumps, and pens. Most people get it right, and it’s getting easier and easier to join the majority.