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Insulin is the foundation of treatment for many people with diabetes. If you’re a diabetic, your body either can’t produce enough insulin or can’t use insulin efficiently.

People with type 1 diabetes, and some with type 2 diabetes, have to take several injections of insulin per day.

The insulin keeps blood sugar in a normal range and prevents high blood sugar levels. This can help prevent complications. The amount of insulin you should take can be determined in several different ways:

Fixed-dose insulin

With this method, you take a certain set amount of insulin units at each meal. For example, you may take 6 units at breakfast and 8 at dinner. The numbers don’t change based on your blood sugar readings or the amount of food you eat.

While this may be easier for people just starting insulin, it doesn’t account for pre-meal blood sugar levels. It also doesn’t factor in the varying amounts of carbohydrates in a given meal.

Carbohydrate to insulin ratio

In this method, you take a certain amount of insulin for a certain amount of carbohydrates. For example, if your breakfast carb to insulin ratio is 10:1 and you eat 30 grams of carbohydrates, you would take 3 units before breakfast to cover your meal.

This method also includes a “correction factor” that accounts for your pre-meal blood sugar. For example, let’s say you want your blood sugar to be under 150 mg/dL before meals, but it’s at 170.

If you’ve been told to take 1 unit of insulin for every 50 you’re over, you would take 1 additional unit of insulin before your meal. While this takes a lot of practice and knowledge, people who can manage this method can keep better control of their post-meal blood sugar levels.

Sliding-scale insulin therapy (SSI)

In the sliding-scale method, the dose is based on your blood sugar level just before your meal. The higher your blood sugar, the more insulin you take.

SSI therapy has been around since the 1930s. It’s most often used in hospitals and other healthcare facilities because it’s easy and convenient for the medical staff to administer.

SSI has become controversial in recent years because it doesn’t control blood sugar very well.

In most sliding-scale insulin therapy regimens, your blood sugar is taken using a glucometer. This is done about four times a day (every 5 to 6 hours, or before meals and at bedtime).

The amount of insulin you get at mealtime is based on your blood sugar measurement. In most cases, fast-acting insulin is used.

Experts have raised a few concerns about using sliding-scale insulin therapy. They include:

Poor blood sugar control

An article in American Family Physician looked back at nearly 40 years’ worth of studies on sliding-scale insulin.

It found that no study clearly showed SSI was effective at controlling blood sugar, even though most hospital patients were given this method. Instead, SSI often leads to a rollercoaster effect.

Also, SSI isn’t very effective at lowering high blood sugar. Sometimes it can cause blood sugar to dip too low. That may be why studies have found that people using this method often have longer hospital stays than if they were given fixed insulin doses.

No personalization

Sliding-scale insulin therapy doesn’t take into account personal factors that can affect your blood sugar and insulin needs. Personal factors include:

  • Diet: What you eat can affect your need for insulin. For example, if you eat a meal that’s high in carbohydrates, you’ll need a higher dose of insulin than if you ate a low-carbohydrate meal.
  • Weight factoring: A person who weighs more may need more insulin. If a 120-pound person and a 180-pound person each get the same dose, the person weighing 180 pounds may not receive enough insulin to lower their blood sugar.
  • Insulin history: The dose doesn’t account for how much insulin you’ve needed in the past. It also doesn’t consider how sensitive you’ve been to insulin’s effects.

Doses reflect current insulin needs

With SSI, you get a dose of insulin that’s based on how well your previous dose of insulin worked. That means the dose isn’t based on the amount of insulin you might actually need for this meal.

If you received a rapid-acting dose of insulin with lunch, it may have brought your blood glucose within its target range. But this may lead to too little insulin being used for your next meal.

Sometimes the doses are given too close together or stacked, which causes their effects to overlap.

Many organizations, including the The Society for Post-Acute and Long-Term Care Medicine and the American Geriatrics Society, don’t recommend that hospitals, nursing homes, and other healthcare facilities use sliding-scale insulin therapy.

Instead, they recommend using basal insulin, with mealtime insulin added as needed. Basal insulin involves long-acting insulin injections that help keep insulin levels steady throughout the day.

Added to this are rapid-acting mealtime insulin and correction doses to regulate blood sugar levels after meals.

Hospitals and other healthcare facilities seem to be listening to these recommendations — today, they’re using SSI therapy less often than before.

Some experts say that sliding-scale insulin therapy should be phased out completely. But one report from the American Diabetes Association says more research still needs to be done.

The report calls for more studies to compare sliding-scale insulin with other insulin regimens before doctors make the final verdict.

You’ll probably only encounter sliding-scale insulin therapy if you’re admitted to the hospital or another healthcare facility. Ask your doctor about how your insulin delivery will be scheduled while you’re there, and what options are available to you.