Sliding Scale Insulin Therapy: Understanding Dosage Charts and Formulas for Safe Use

In India, approximately 77 million people over 18 years have type 2 diabetes, and around 25 million are prediabetic. Moreover, nearly 50% of them are unaware of their blood sugar levels.

Some have inherited it through genes, while others are living with it due to the stress from work and a sedentary lifestyle.

Individuals with diabetes often compromise on the food they love just to keep their sugar levels in check. Moreover, they prick their finger before a meal, testing the blood sugar using a small machine and recording the results. It is an intuitive and routine thing to do to control diabetes.

But technology and science have developed since then, and today there are several ways to monitor and manage blood sugar levels. Among these is the sliding scale insulin therapy, which has been in existence since the 1930s.

Highly employed in hospitals and currently emerging in the home, the sliding scale insulin therapy is a method of controlling insulin dosage according to the actual blood glucose levels. However, as with any other treatment with the use of drugs, proper consumption and knowledge are essential.

Know all about sliding scale insulin and how it works, how to adjust your insulin according to the sliding scale, components of the insulin sliding scale chart, how insulin doses are calculated using the insulin dose sliding scale and much more.

In diabetes, insulin plays a vital role in ensuring that your blood sugar levels are maintained. If you have type 1 diabetes, you need to inject insulin through injections or pumps. In type 2 diabetes, you need to make lifestyle changes and use medications to manage blood sugar levels.

The sliding scale insulin therapy means operating on a chart of insulin dosage. This chart will be assisted by a doctor who considers various factors of a diabetic, such as how well other body organs react to insulin and all the activities that a person indulges in every day. although that does not imply it does not have its difficult areas.

In contrast to fixed dosing, the insulin sliding scale formula is used to determine the quantity of rapid-acting insulin (i.e. regular insulin or human Actrapid) required to correct hyperglycemia. It is generally a short-term application of the scale, and it is often applied to hospitalised patients.

A basic insulin sliding scale chart includes:

• Pre-meal blood glucose ranges (mg/dL)
• Corresponding insulin dosages (in units)
• Time of administration (usually before meals and bedtime)
• Type of insulin used (e.g., human Actrapid sliding scale, rapid-acting analogues)

The sliding scale insulin formula is not universal, but one can follow this general approach: (Current Blood Glucose – Target Glucose) ÷ Correction Factor = Units of Insulin

Let’s break it down:

• Target Glucose: What the doctor usually targets, which is generally 100-120 mg/dL
• Correction Factor: A number showing to what extent a one unit insulin injection will reduce the glucose level (usually 30 50mg/dl of insulin with fast-acting insulin)

Let's take an example: If a patient’s current blood sugar is 220 mg/dL, the target is 120 mg/dL, and the correction factor is 40: (220 – 120) ÷ 40 = 2.5 units (rounding to two or three units depending on the chart or device used)

• Monitor glucose level before every meal: Before administering insulin, blood glucose needs to be measured with a glucometer, then the administration of insulin at the sliding scale of the insulin formula has to be followed.
• Use short-acting or regular insulin: Sliding scale regular insulin, e.g. Actrapid, is best to use as it matches the body's natural insulin peak after every meal. The newer analogues (e.g. lispro, aspart) are used on a prescription basis.
• Always follow the prescribed dosage chart: Adhere to the custom insulin dose sliding scale as given by your health professional. The doses generally vary with individual patients and are determined by age, renal functioning, activity and eating habits.

• Standard Sliding Scale: Uses fixed ranges and corresponding doses.
• Dynamic Sliding Scale: Adjusted daily based on response.
• Hai Sliding Scale: A hospital-adapted intensive insulin chart used in critical care settings.

Here are some of the commonly used insulin types:

• Human Actrapid Sliding Scale: Regular insulin with an onset of 30 minutes.
• Rapid-Acting Analogues: Like insulin lispro (Humalog), which acts faster.

Advantages:

• Simple and easy to understand
• Fast correction of high blood glucose
• Useful in hospital settings for fluctuating sugar levels

Disadvantages:

• Reactive, not preventive
• Doesn’t consider carbohydrate intake
• Can miss trends in glucose variation
• Risk of hypoglycaemia if meals are missed

This is why most specialists recommend using sliding scale insulin with proper control, or in combination with a basal-bolus insulin prescription.

Here is a reference insulin sliding scale dose chart for Actrapid:

Check doses with a doctor always, especially when you have a condition that may influence the absorption of insulin, such as kidney disease or gastroparesis.

Doctors often prescribe sliding scale insulin in the following cases:

• Hospitalised patients with temporary blood glucose spikes
• Patients transitioning from oral medications to insulin
• Situations requiring short-term glucose control (surgery, infection)
• As a correctional therapy in combination with long-acting insulin

Sliding scale therapy is, however, not supposed to be solely prescribed as a form of long-term diabetes control measure since it is reactive. It is always best to follow your doctor’s advice or consider a second opinion if necessary, without making any changes to your insulin treatment.

Q. What is a sliding scale for insulin use?

A. A sliding scale for insulin use adjusts insulin dosages based on real-time blood glucose levels. It’s a reactive method, where higher blood sugar readings receive higher insulin doses. Often used in hospital settings or short-term outpatient care, it helps manage sudden spikes in glucose during illness, surgery or treatment transitions.

Q. How to read an insulin sliding scale dosage chart?

A. An insulin sliding scale dosage chart lists blood glucose ranges alongside corresponding insulin doses. After checking blood sugar, match your reading to the appropriate range on the chart to determine the insulin dose. Charts are personalised, so always follow the one prescribed by your doctor or diabetes care specialist.

Q. What is the sliding scale insulin formula?

A. The sliding scale insulin formula typically follows: (Current Blood Glucose – Target Glucose) ÷ Correction Factor = Insulin Dose It helps calculate how much rapid-acting insulin is needed to bring blood sugar back to the target range. Doctors customise this based on your sensitivity, health condition, and lifestyle factors.

Q. How to use the Actrapid sliding scale for insulin?

A. Actrapid, a short-acting insulin, is often used in sliding scale therapy. Before meals, check your blood glucose, refer to the Actrapid-specific sliding scale chart, and inject the recommended dose. Ensure timing aligns with meals, and monitor for hypoglycaemia. Use under strict medical supervision, especially in hospital or transitional care settings.

Q. When do doctors recommend sliding scale insulin therapy?

A. Doctors recommend sliding scale insulin therapy for short-term glucose control during hospital stays, infections, surgeries, or treatment changes. It’s also used when blood sugar fluctuates significantly. While convenient for temporary management, it’s usually not advised as a long-term strategy due to its reactive, rather than preventive, nature.