When Is Insulin for Diabetes No Longer a Good Idea?

It's embarrassing to admit, but doctors don't always follow their own advice or the advice of the expert panels who produce "best-of-care" guidelines.

Credit: @RLTheis via Twenty20

Proving just that point is a recent study from the health care giant Kaiser-Permanente that followed 21,000 older adults with Type 2 diabetes over four years.

Current guidelines recommend either reducing or stopping insulin therapy as patients age or their health status declines. That recommendation comes with no specific age cut-off, but nearly 20% of the study's participants were still being treated with insulin as they entered the study at age 75.

Over the four years of the study, researchers found that patients with the poorest health status were the most likely to be on insulin at the beginning of the study, and the least likely to have had their insulin stopped by the end of the study.

Conversely, those in good health were the least likely to have started the study on insulin and the most likely to have had their insulin stopped.

Oops: That's the reverse of expert recommendations. As the researchers concluded, there's work to be done.

Wayward physician practices aside, it might seem counterintuitive to deny an important medication like insulin to the sickest patients with Type 2 diabetes. But the recommendation has to do with the risk/benefit ratio — weighing the risks of a drug, surgery or treatment against the benefits to be derived.

Controlling Type 2 diabetes offers critical cardiovascular health benefits, but only in the long term. Generally speaking, it takes months and years — not days and weeks — of uncontrolled diabetes to cause the blood vessel damage that we refer to as atherosclerosis. So when a patient with diabetes gets to the steeper, "black-diamond" part of the mortality curve, either by age or cumulative disease, he or she may not live long enough to realize the benefits of tighter blood sugar control.

Because synthetic insulin is "au natural" — identical to what our body makes — low blood sugar (hypoglycemia) is typically its only side effect. Like a battery-powered toy that's running out of juice, a hypoglycemic patient gets fatigued and increasingly listless.

On rare occasions, hypoglycemia can be fatal, but most episodes end up just being energy sapping, annoying, discouraging and disruptive. Life gets put on hold until some sugary food or drink can be found and the body's metabolism resettled. And, of course, the sufferer can't help but wonder if it would be better to settle for looser diabetic control rather than experience another episode.

A patient's decision to stop or continue insulin should always be made with a physician, as circumstances vary with each individual.

Keep in mind that older people with Type 2 diabetes plus other health problems can be at higher risk of hypoglycemia. For example, dementia or visual problems can increase the risk of misdosing insulin; food access issues can lead to inconsistent or missed meals; insulin tends to build up in the system if kidney function declines and weight loss from cancer or other advanced diseases generally means insulin dosing will need to be reduced.

Many older patients have orthopedic or neurological issues that put them at increased risk of falling, and hypoglycemia only adds to that risk. Older patients rarely die directly from something as common as a fall-related hip fracture, but the immobility that comes in the recovery process is a serious health risk. The phrase "move it or lose it" is sound, science-based advice. When we don't move, the physiologic wheels can fall off in a hurry.

The good news for older adults with Type 2 diabetes is that they aren't left high and dry. There are a number of medications that don't carry the side effect of hypoglycemia.

Leading that list is a drug called metformin, considered first-line therapy for adult-onset diabetes because it's generally well tolerated, doesn't lead to low blood sugars and is very affordable.

If metformin isn't enough, there are other options, and you can find them in an article by the American Diabetes Association titled "Pharmacological Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes—2019." These four medication groups have long funky names that even a biochemist couldn't remember, but they go by the abbreviations SGLT2 inhibitors, TZDs, GLP-1 agonists and DPP-4 inhibitors.

Seeing how an in-depth conversation about these drugs could easily put you, the faithful reader, into the equivalent of a hypoglycemic coma that wouldn't respond to a barrel of orange juice, I will make this brief:

• TZDs are an attractive option because they are low-cost and come in a pill form. But those benefits are tempered by the fact that they can cause weight gain (counterproductive in diabetes) and fluid retention (a problem for patients with heart failure and kidney problems).
• SGLT2 inhibitors and DPP-4 inhibitors both come in pill form, but are of intermediate potency and more expensive.
• GLP-1 agonists are pricey, too, and only available as an injection. But they, along with SGLT2 inhibitors, are becoming popular for their proven cardiovascular benefits.

Although none of these four drug classes cause hypoglycemia, they all have potential side effects and risks to consider. And since beauty — and the risk/benefit ratio of any treatment — is ultimately in the eye of the beholder, one can reasonably decide to continue with insulin despite deteriorating health or advancing age (remembering that biological age is more important than one's chronologic/calendar age).

In particular, some people with Type 2 diabetes no longer produce any insulin on their own, and it may be hard to obtain even reasonable blood sugar control without it. And although hypoglycemia is rightly feared, significant and persistent blood sugar elevations are not completely harmless. They can cause dehydration, fatigue, vision change and slow wound healing and increase infection risk.

If older patients do continue with insulin, it's common practice to stick with a daily, long acting insulin. These carry a lower of risk of hypoglycemia compared to shorter acting insulins, which are designed to quickly capture the carbohydrate load of a meal.

Like a turtle,  a diamond cutter or Father Time playing the back nine, slow and smooth wins the day.