When it comes to diabetes management, insulin often becomes part of the conversation. For some, it’s needed right away; for others, it may come later as diabetes progresses. Insulin plays a vital role in helping the body use and regulate glucose and understanding how it works can empower you to feel more confident in your care. In this post, we’ll explore the basics of insulin, why it’s used, and what it means for day-to-day diabetes management.
In type 1 diabetes, the pancreas no longer produces insulin at all, which means people with type 1 must inject insulin to replace what their body cannot make. Whereas in type 2 diabetes, the body initially still makes insulin, but it may not use it effectively (insulin resistance). Over time, as the disease progresses, the pancreas may produce less and less insulin. When this happens, insulin therapy is often needed to help keep blood sugar levels within a safe range. Starting insulin does not mean that you’ve ‘failed’, but rather the progression of the disease and an important conversation to have with your healthcare provider.
Disclaimer: This article is for educational purposes only and is not intended to provide medical advice, diagnosis, or treatment. The information shared here—and in any linked content—should not replace guidance from your healthcare provider or registered dietitian. Always consult your care team for personalized medical support and recommendations.
What is Insulin?
Insulin is a hormone made by the pancreas that helps move glucose (sugar) from the bloodstream into the body’s cells to be used for energy or stored for later. Without sufficient insulin, blood sugar levels rise, which, over time, can lead to health complications. Types of insulin are generally distinguished by four main factors:
- Intended use – when the insulin is meant to be taken or injected.
- Onset – how long it takes after injection for the insulin to enter the bloodstream and begin working.
- Peak time – the period when the insulin is working at its maximum strength to lower blood glucose.
- Duration – how long the insulin continues to lower blood glucose levels.
Rapid-Acting Insulin
Rapid-acting insulin is commonly used in the management of different types of diabetes. It can be delivered through a syringe, insulin pen, pump, or patch, and is injected into the fatty tissue so it can enter the bloodstream.
- Intended use: Typically taken about 15 minutes before eating, used to correct high blood sugar, or delivered as a continuous basal drip through an insulin pump.
- Onset: Begins working in about 15 minutes.
- Peak time: Reaches maximum effect 1–2 hours after injection.
- Duration: Lasts about 4–6 hours.
Regular or Short-Acting Insulin
An older but still widely used option, short-acting insulin works slightly slower than rapid-acting insulin. Taken usually before meals to help manage post-meal blood sugar rises. This type of insulin can be taken by needle/syringe and vial, pen, or via a pump.
- Intended use: Injected 30 minutes before eating to cover carbohydrate intake.
- Onset: 30–60 minutes
- Peak time: 2–4 hours
- Duration: 5–8 hours
Intermediate-Acting Insulin
Offering extended coverage, this insulin is often used to manage blood sugar levels between meals or overnight. Similar to long-acting insulin and quite different from rapid and regular insulin. Typically combined with rapid and regular insulin to provide more comprehensive coverage. Available as a pen or a vial, the injection is given under the skin using a needle or a pen. This is not to be used in an insulin pump.
- Intended use: Covers blood sugar needs for part of the day or overnight; two injections/day
- Onset: 1–3 hours
- Peak time: 4–10 hours
- Duration: 10–16 hours
Long-Acting Insulin
Designed to provide a steady, “background” level of insulin throughout the day and night. It does not have a pronounced peak, which makes it helpful for maintaining stable blood sugar levels between meals and overnight.
- Intended use: Taken once or twice daily to provide basal insulin coverage.
- Onset: 1–4 hours
- Peak time: Minimal to none (steady release)
- Duration: Up to 24+ hours, depending on the type
Premixed Insulin
A combination of two insulins—usually one rapid- or short-acting and one intermediate-acting—formulated together to simplify dosing. There are many different mixtures that help cover blood sugar levels; however, they offer less flexibility with meal timing. One common premixed insulin is Novolin 70/30, a mixture of 70% intermediate-acting insulin and 30% regular insulin.
- Intended use: Taken before meals to cover both immediate and longer-term insulin needs.
- Onset: Depends on mix (usually 15–30 minutes)
- Peak time: 1–4 hours, with a second peak 4–12 hours later
- Duration: Up to 24 hours
When it comes to insulin, balance is critical. Taking too much insulin can cause hypoglycemia (low blood sugar), which may lead to shakiness, confusion, sweating, dizziness, or, in severe cases, seizures or loss of consciousness. On the other hand, taking too little insulin can result in hyperglycemia (high blood sugar), which, if prolonged, may lead to serious complications such as diabetic ketoacidosis (DKA). This is why it’s essential to follow your healthcare team’s guidance on dosing and to monitor your blood sugar levels regularly.
How To Treat Hypoglycemia
If you experience hypoglycemia (blood sugar below 70 mg/dL), the recommended treatment is the 15-15 rule: consume about 15 grams of fast-acting carbohydrate—such as 4 ounces of juice, regular soda (not diet), 3–4 glucose tablets, or 1 tablespoon of honey or sugar. Wait 15 minutes, then recheck your blood sugar. If it’s still low, repeat the process. Once your blood sugar returns to normal, follow up with a small snack or meal that includes protein and complex carbohydrates to help keep your levels stable.
If your blood sugar level is low, you need to act quickly and get it up as quickly as possible. That is the reason to use the fast-acting carbohydrate. You do not want to consume something that contains protein, fat, or fiber, as this can slow down the absorption process and take too long to raise the blood sugar level. Having a low blood sugar level can be a life-threatening situation if the blood sugar is not raised quickly enough. Other examples of fast-acting carbs to have on hand: applesauce pouches, fruit juice boxes, glucose tablets.
