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Unintended Consequences

“Best laid plans of mice and men often go awry” is especially true in the complex world of diabetes management. Here, medicines, behavior, quirks of the human body, and just plain luck collide, with results that can be hard to predict. Sometimes the best of intentions leads to the worst of outcomes.

But precisely because diabetes management can be so messy and complicated, using your wits can get you far ahead. Read each of the following “case studies” and see if you can guess what will happen next, or what led to the unexpected outcome. The correct answer and a brief explanation follow each case.

Jim and the hypo
Jim has Type 2 diabetes and uses mealtime insulin along with a long-acting (basal) insulin to treat it. After spending some time with a registered dietitian who is also a certified diabetes educator, he has turned over a new leaf in his self-care. Among other things, he has started eating a banana every day with his breakfast to boost his fruit and vegetable intake. He has also started checking his blood glucose more often, and one morning he is shocked to discover that his meter reading is 318 mg/dl three-and-a-half hours after breakfast.

To bring down his high blood glucose level, Jim takes a correction bolus of insulin lispro (brand name Humalog), using a correction factor of one unit of insulin per 20 “points” (mg/dl) above his target level. About an hour and a half after giving himself 10 units with an insulin pen, Jim begins to feel shaky and light-headed. He checks his blood glucose again and is shocked to discover it has dropped to 41 mg/dl.

What do you think happened to Jim?

A. He did his math wrong and took too much insulin.

B. He did his math right, but his correction factor was wrong; one unit of Humalog lowers blood glucose by more than 20 mg/dl in anyone with diabetes.

C. His first blood glucose reading was wrong.

D. He “stacked” his insulin; that is, he didn’t account for the insulin still active in his body from the dose he took before breakfast.

And the correct answer is…

C. His first blood glucose reading was wrong. Bananas are notorious for leaving a sugary residue on the skin that can throw off blood glucose meter readings. Other fruits can do the same, as can many perfumed hand lotions. Some other things that can cause errors in your readings include not getting enough blood on the strip and using a miscoded meter.

Answer D, “stacking” his insulin, could also come into play to some degree. Jim checked his blood glucose level three-and-a-half hours after eating, so there was likely to be some active insulin left in his body from his breakfast bolus; Humalog has about a four-hour glucose-lowering effect in most people. That said, Jim’s remaining breakfast insulin would be unlikely to pack enough of a punch to cause such a dramatic drop so early after the correction. Mild hypoglycemia between three and three-and-a-half hours after the correction injection could have come from “stacking.”

As for answers A and B, Jim did his math right. He subtracted 115 (a typical target number) from his blood glucose level of 318 mg/dl to get 203, the number of “points” above his target level. He then divided 203 by his correction factor of 20 to get a dose of 10.15 units, which he sensibly rounded down to 10. There is no right or wrong amount of insulin; everyone needs a different amount. In general, people with Type 2 diabetes are more resistant to insulin and require more of it to bring down high blood glucose or to “cover” carbohydrate. People with Type 1 diabetes are generally more sensitive to insulin and therefore require less of it. A typical correction factor — the expected drop in blood glucose, in mg/dl, from one unit of injected insulin — for a person with Type 2 diabetes is 25, while for a person with Type 1 it is typically closer to 50.

Eve and the statin
Eve is a 37-year-old woman of normal weight. While she comes from a family with a significant history of Type 2 diabetes, her blood tests have always shown high-normal fasting blood glucose levels, just below the prediabetes threshold. Her cholesterol, however, is another matter; it’s frightfully high, so her doctor starts her on 80 milligrams of the statin drug atorvastatin (Lipitor).

What do you think happens to Eve after she starts taking Lipitor?

A. She develops diabetes.

B. She experiences stomach cramps and stops taking the drug two days later.

C. Her health insurance company refuses to pay for the Lipitor, insisting on the documented failure of a generic drug first.

And the correct answer is…

A. Yes, as it turns out, the statin class of drugs really can raise blood glucose. While current evidence does not support the idea that this glucose-raising effect is ever a sole cause of diabetes, it may serve as the tipping point for at-risk people. Because Eve had a significant family history of Type 2 diabetes and was approaching the “magic age” of 40 (when someone who has prediabetes would be expected to develop full-fledged diabetes), the drug pushed her over the edge. Of course, the risk that taking a statin drug may lead to diabetes must be balanced against the health threat posed by “frightfully high” cholesterol.

As to answer B, the most common negative side effect of statin drugs isn’t stomach problems but myalgia, aching deep in the muscles (like when you feel the flu coming on). The scenario in answer C probably would have happened in years past, but in late 2011, Lipitor saw its patent protection expire, meaning that it can now be produced by generic manufacturers. Under its generic name of atorvastatin, the drug is covered by most health insurance plans to the tune of about $10 a month.

Regina and the insulin pen
No matter how much fast-acting insulin Regina takes, it never makes a dent in her blood glucose readings. Her diabetes educator is alarmed to hear that Regina, who weighs 118 pounds, now takes up to 60 units of Humalog at a time, yet still sees blood glucose readings in the mid-300s. A careful review of her log book shows her readings before and two hours after attempted corrections, and sure enough, there is no significant difference. In fact, sometimes her blood glucose level is higher after an insulin injection. Her insulin is new and properly stored, and she uses a fresh pen needle for every injection.

What do you think is the cause of Regina’s problem?

A. She has not been rotating her injection sites and is injecting into scar tissue.

B. She is allergic to the insulin.

C. She is using the insulin pen incorrectly.

And the correct answer is…

C. This is based on a true story. After injecting the needle into her skin, Regina was simply spinning the pen dial back to zero rather than depressing the plunger. She was resetting the pen but receiving no insulin whatsoever. The only reason I figured this out is that I asked her how long her pens were lasting. She told me she’d been using the same pen for about a month. With injections that high in volume, each pen should have lasted only a few days. (I’m no genius, but I have my good days!)

The moral of this story is that if insulin isn’t acting the way you think it should be, make sure you are actually getting it the way you think you are.

As to answer A, many different factors can interfere with insulin delivery or absorption, including injecting into scar tissue. However, scar tissue tends to be hit-or-miss. If some injections seem not to work while others lower blood glucose as expected, scar tissue should be a prime suspect. In this case, all of Regina’s injections were failing, so the culprit had to be something else. As to insulin allergies, these typically show up as skin reactions: rashes, bumps, itchy areas, or bruising. While ranging from mildly annoying to highly vexing, allergies don’t usually have any impact on the glucose-lowering power of insulin.

Thomas and the moving day
Poor Thomas. Being a nice guy, he agrees to help his two friends move to their new apartment. But his buddies stay out really late the night before the move, so Thomas ends up doing the lion’s share of the work — including moving some boxes that are really too heavy for one person to move.

By the end of the day, Thomas is sure he has pulled something in his back. Over the next two days, the pain gets progressively worse. Finally, getting worried, he decides to visit the emergency room. He doesn’t tell the ER staff that he was recently diagnosed with Type 2 diabetes because it simply doesn’t occur to him. He’s attempting to control his blood glucose by losing weight, exercising more, and making healthier food choices, and he’s not taking any diabetes drugs. The ER doctor diagnoses a pulled muscle and prescribes the steroid prednisone.

What do you think happens next?

A. Thomas is surprised to find that his blood glucose numbers are suddenly much lower.

B. Thomas’s blood glucose level remains stable, and his back is better in days.

C. That night, Thomas is stunned to see the highest blood glucose numbers he’s ever seen on his meter.

And the correct answer is…

C. Steroids are notorious for raising blood glucose levels, and if the ER doctor had known Thomas had Type 2 diabetes, she probably would not have prescribed one. Some other drugs can also raise or lower blood glucose, or interfere with the effectiveness of blood-glucose-lowering drugs.

As to answers A and B, steroids reliably raise blood glucose, often even in people without diabetes; they never lower it. But at least they do work. Thomas’s back gets much better within days, even as his high blood glucose is really beginning to scare him. The good news is that once he finishes his course of prednisone, his blood glucose will return to the levels he was seeing before he started taking the drug.

Roy and the baked potato
Roy is 79 years old. He has Type 2 diabetes in adequate, if not stellar, control. His blood pressure has been above-target, however, so his doctor adds a beta-blocker to his existing blood pressure medicines and advises a low-sodium diet. Roy returns for a follow-up visit complaining of nausea, fatigue, and muscle weakness.

What do you think is happening to Roy?

A. He is suffering from a common, but not serious, side effect of beta-blockers.

B. His wife made him stop using salt too quickly.

C. He is allergic to the new drug.

D. He’s experiencing the effects of a drug interaction between the beta-blocker and one of his other prescription drugs.

And the correct answer is…

B. His wife made him stop using salt too quickly. Then, because he complained so much about how his baked potato tasted flat, she picked up some salt substitute made from potassium chloride. Reading on the label that it was “salt-free,” Roy used the product even more liberally than he would have used table salt — resulting in a potassium overdose known as hyperkalemia, which can be fatal.

As to answer D, drug interactions can be tricky to ferret out, especially in people who take several drugs. But the increasing use of electronic medical records by both health-care providers and pharmacies is making potential interactions more likely to be discovered before a prescription is filled.

While people do sometimes have unique or rare side effects from drugs, the side effects of beta-blockers would more typically be edema (swelling) of the feet or hands, or easy bruising. An allergic reaction to a beta-blocker might lead to a rash, itching, or trouble breathing. You don’t need to be a doctor to know this; the patient information sheet included with every prescription drug lists its common side effects as well as signs of an allergic reaction. You should always take the time to review this information when you start taking any drug.

Billie’s blurry vision
Billie uses rapid-acting insulin glulisine (Apidra) as part of her treatment plan for her Type 2 diabetes. One afternoon she starts to feel woozy, and she notices that her vision is a little blurry. She remembers reading somewhere that high blood glucose can cause blurred vision, so she grabs her insulin pen and injects a few units to fix the problem.

What do you think happens next to Billie?

A. Her blurry vision clears up promptly.

B. Her vision doesn’t change, so she makes an appointment with her eye doctor.

C. She gets even woozier, checks her blood glucose, and finds that she is hypoglycemic.

And the correct answer is…

C. And then her diabetes educator tells her to have her head examined. Never, ever take insulin without first checking your blood glucose level! Blurry vision is one of those symptoms that can be caused by either high or low blood glucose, although Billie was correct to think that high blood glucose is more commonly the cause. But feelings or symptoms, while often crucial warning signs that something is wrong, should not be the sole basis for taking insulin (or most other drugs). Use your feelings to guide you to your meter to check your blood glucose level. Had Billie done this, she would have realized her blood glucose was low and could have treated it, rather than taking insulin to lower her blood glucose even more.

There is also the matter of “just injecting a few units to fix the problem.” Even if Billie’s suspicions of high blood glucose had been confirmed by her meter, she would still need to calculate how much insulin to take, not just guess.

And even if Billie had had high blood glucose and done everything right, her vision still would not have cleared up “promptly.” It would have taken several hours to clear up. Of course, had Billie’s blood glucose level returned to a normal range with no improvement in her vision, calling the eye doctor would then be a good idea.

Improving your odds
Everyone makes mistakes in their diabetes management occasionally or has a run of bad luck, and you will too. But you can stack the odds in your favor by being informed, asking questions, and using the tools at your disposal (such as your blood glucose meter) to help you decide how to act to fix a problem.

Read. The patient information sheets that come with prescription drugs may not be the most thrilling reading you’ve ever done, but they contain useful information that can help you avert problems or even disasters. Some other boring but useful sources of information include over-the-counter drug labels, food labels, and any handouts your health-care providers give you about conditions you have. So sit down with a highlighter and slog through them, highlighting any parts that seem particularly important to you.

Ask questions. When you meet with your doctor, diabetes educator, pharmacist, and any other health-care professionals on your diabetes team, take the opportunity to ask any questions you might have about your care, your diabetes management routines, your medicines, etc.

Listen. Listening may be the part of communication that’s neglected the most. So once you’ve asked your questions, listen carefully to the answers, and take notes to help you remember what was said.

Check. If you think your symptoms are being caused by high or low blood glucose, check your blood glucose level with your meter before doing anything. The exception to this rule is when you suspect low blood glucose and don’t have your meter handy. In this case it’s safer to treat for low blood glucose (so that you don’t pass out or have an accident) and then check when you can.

Double-check. Double-check the information you receive (particularly if you hear some medical information from a friend or read it on a message board) as well as your memory of what you thought your doctor said (by checking your notes or any printed material you may have received from a health-care professional). In addition, double-check your efforts to solve your health problems by evaluating the effects of your intervention. If you’ve taken some action to raise or lower your blood glucose level, check it again to see whether your efforts resolved the problem.

Be prepared. Who are you going to call if a minor problem — or a crisis — arises in your diabetes management? Give this some thought while you’re not having a problem, and assemble a list of contact information for the people you could call: your doctor’s office, your diabetes educator, a friend or relative who could act on your behalf or drive you to the doctor’s office, the pharmacy you use, your health plan’s on-call nurse, a local urgent-care center, etc.

Learn from your mistakes. There may be times when you realize there was nothing you could have done to avoid a mistake or an unintended consequence. But if you see that you could have avoided it by doing something differently — or you now see how to avoid repeating the same mistake in the future — be willing to learn from your mistake so that it doesn’t happen again.

Statements and opinions expressed on this Web site are those of the authors and not necessarily those of the publishers or advertisers. The information provided on this Web site should not be construed as medical instruction. Consult appropriate health-care professionals before taking action based on this information.