Sliding scale insulin therapy involves following a chart of insulin dosages. A doctor will help a person with diabetes create this chart based on factors like how their body responds to insulin and their daily activity.
Insulin therapy aims to manage blood sugar levels to prevent symptoms and the risk of complications from diabetes.
The sliding scale is one way to determine how much insulin to take before each meal. Doctors developed it several decades ago as a guide to insulin dosage.
Clinical guidelines typically recommend against using sliding scale insulin as the sole method of insulin management. They instead recommend alternative methods, such as basal-bolus insulin.
However, some healthcare professionals may still temporarily use sliding scale insulin therapy for people with noncritical type 2 diabetes who are in the hospital.
The sliding scale is a chart of insulin dosages. A doctor creates this chart with an individual, so each one is different. The doctor bases it on how a person’s body responds to insulin, their daily activity, and a carbohydrate intake that they will agree on.
Insulin dosage will vary depending on two factors:
- Pre-meal blood sugar level: This usually appears on the left-hand side of the chart, from low to high, with higher doses toward the bottom. The higher the blood sugar someone has, the more insulin the person will need.
- Mealtime: This may appear along the chart’s top row. This row shows breakfast, lunch, and dinner.
The dose will change throughout the day. This is because insulin sensitivity — the way the body responds to insulin — can change as the day progresses.
The composition of meals can also change throughout the day, and the doctor may take that into consideration.
Reading the chart
To work out the right dosage using a sliding scale, people may need to use the following steps:
- Test their blood sugar level.
- Find the matching blood sugar value along the chart’s left-hand column.
- Slide horizontally along that value’s row until they reach the current meal.
- Take a dose that matches the number where the two values meet.
The person should test their blood sugar levels before mealtimes, depending on the type of insulin they use.
Different types of insulin work over different periods of time. If a person uses a rapid-acting insulin, they may need to take it around 15 minutes before a meal.
Along with these mealtime rapid-acting doses, people may also take a long-acting insulin dose once or twice per day. The aim of this is to set a stable baseline blood sugar level for the body to work around.
The American Diabetes Association (ADA) 2022 Standards of Medical Care in Diabetes strongly discourages the long-term use of only sliding scale insulin in an inpatient setting.
However, a 2021 study suggests that hospitals may still use sliding scale insulin for people with type 2 diabetes in a noncritical care setting, despite these recommendations.
The researchers found that 31.4% of 25,813 patients with type 2 diabetes had sliding scale insulin treatment alone. They concluded that sliding scale insulin treatment may be a suitable option for people with mild hyperglycemia.
According to a 2022 national cohort study, official guidelines advise against using sliding scale insulin for people with type 2 diabetes 1 week after admission to nursing homes.
However, the researchers found that 21% of the study’s cohort were still using sliding scale insulin therapy in the second week following nursing home admission. By week 12, this reduced to 16%.
Continuation of sliding scale insulin was more common in people with comorbidities, cognitive impairment, or functional impairment and had a strong association with diabetes-related factors, such as hyperglycemia.
The sliding scale method requires very few daily calculations. People with diabetes may also feel more comfortable following a pre-determined plan. However, these factors make sliding scale treatment very inflexible.
Below are some potential drawbacks of sliding scale insulin therapy:
Inflexible routine
The following factors may contribute to sliding scale insulin’s inflexibility:
- Carbohydrates: The person must consume the same number of carbs with each meal because the chart’s calculations depend on a single carb value. This number should not change from day to day.
- Meal timing: The person needs to eat their meals around the same time each day. If not, their insulin sensitivity may not match the ones the chart uses to work out the dosage for a specific meal.
- Exercise: People should not vary the amount they exercise from day to day. Changes in activity and stress can affect blood glucose levels in a way that the sliding scale cannot account for.
It is challenging for most people to follow these meal and activity restrictions completely. As a result, large changes in blood sugar levels can happen throughout the day.
Blood sugar variability
According to a 2018 review, sliding scale insulin therapy can lead to greater variability in blood sugar levels, meaning people may experience hypoglycemia and hyperglycemia more frequently.
It may also take longer for people to achieve metabolic control.
The doses that a sliding scale chart requires may also be excessive if a person skips meals or is more sensitive to insulin on a given day. If doses build up throughout the day, people could experience a dangerous drop in blood sugar levels.
Surgery complications
A 2017 report suggests that the use of only sliding scale insulin is not acceptable for people around the time of surgery as it can lead to high or low blood sugar levels.
Blood sugar levels that are too high or low may increase the risk of complications, such as infection, during and after general surgery.
In place of the sliding scale model, the ADA recommends the following methods of taking insulin in the hospital:
- Basal insulin: People may also call this background insulin. Basal insulin involves taking long-acting or intermediate-acting insulin to maintain steady bloody sugar levels between meals or at night.
- Basal plus bolus correction: This involves using both basal and bolus insulin. Bolus insulin involves taking short-acting or rapid-acting insulin before or at meals. Rapid-acting correction insulin may be necessary to bring down high blood sugars even when not eating.
- Intravenous insulin infusion: A person intakes insulin continuously through a vein.
Basal insulin or basal plus bolus regimens are suitable for noncritical hospital patients who cannot take anything by mouth or who have an unfavorable nutritional intake.
A basal, prandial, and bolus regimen is the ADA’s recommendation for noncritical hospital patients who have good nutritional intake.
Continuous intravenous insulin infusions may be the most suitable regimen for hospital patients in a critical situation.
Insulin administration techniques
The most suitable insulin administration method varies from person to person. A healthcare professional can help someone determine the best type for them.
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- Syringe: A syringe delivers insulin using a needle. A doctor will advise someone on how much insulin they need to inject. They may require less training than other methods, but people may find them less discreet.
- Insulin pens: Insulin pens can be prefilled or use insertable cartridges. People may find insulin pens more convenient and comfortable than syringes, but they are not compatible with all types of insulin.
- Insulin pump: An insulin pump administers a dose of rapid-acting insulin every hour through a tube in the fatty layer under the skin. People must calculate the dose themselves.
- Insulin inhaler: This involves taking ultra-rapid insulin before meals using an oral inhaler. People may also need to use an injectable long-acting insulin.
Sliding scale insulin therapy involves using a chart with preestablished insulin doses to maintain blood sugar levels. However, clinical guidance no longer recommends only using this method.
Good blood sugar management can prevent complications and can help people live a healthier and longer life.
People can speak with a healthcare professional about the various insulin regimens and administration methods to learn the most suitable option.
