Getting Started with Insulin if You Have Type 2 Diabetes
By Frida Velcani
New to insulin? Learn about insulin dosing and timing and how often to test your blood sugar levels if you have type 2 diabetes.
If you have type 2 diabetes, it is likely that your treatment regimen will change over time as your needs change, and at some point, your healthcare professional may suggest that you start taking insulin. While this might feel scary, there are millions of others living with type 2 diabetes and taking insulin, so it’s definitely manageable.
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Type 2 diabetes can progress with time, which means that it gets more difficult for a person’s body to regulate glucose levels. The body’s many cells become less responsive to insulin (called increased insulin resistance), and the specific cells in the pancreas that produce insulin make less of it (called beta cell insufficiency). This is not necessarily related to a person’s diabetes management, and it is likely not possible to prevent.
For many people, adjusting lifestyle factors such as a reduced calorie diet and increased physical activity are key to keeping blood glucose levels stable and in a target range. Healthcare professionals may also recommend that people with type 2 diabetes take additional medications like metformin, DPP-4 inhibitors, SGLT-2 inhibitors, or GLP-1 agonists to their treatment plan to improve glucose management, reduce A1C, lose weight, or support heart and kidney health.
After 10 to 20 years, many people with type 2 diabetes will begin insulin therapy, although every person’s journey with type 2 diabetes is different. This happens when lifestyle changes and medications aren’t keeping your glucose levels in your target range. It is important that you start treatment as early as possible to avoid persistent hyperglycemia (high blood sugar), which can lead to long-term health complications affecting your heart, kidneys, eyes, and other organs.
The key to transitioning to insulin is knowing your options. Some people taking insulin need to use both a basal (long-acting) and a prandial (rapid-acting or “mealtime”) insulin each day, while others may only need to use basal insulin. Learn about your options here.
Basal (long-acting) insulins are designed to be injected once or twice daily to provide a constant background level of insulin throughout the day. Basal insulins help keep blood sugars at a consistent level when you are not eating and through the night but cannot cover carbohydrates (carbs) eaten for meals or snacks or glucose spikes after meals.
Some people use other medications, like GLP-1 agonists, to help cover mealtimes. GLP-1/basal combination treatments for people with type 2 diabetes combine basal insulin with GLP-1 agonist medication in one daily injection. This combination can effectively lower glucose levels while reducing weight gain and risk of hypoglycemia (low blood sugar). Learn more here.
Prandial (rapid-acting or “mealtime”) insulins are taken before mealtime and act quickly to cover carbohydrates eaten and bring down high sugar levels following meals. Ultra-rapid-acting prandial insulins can act even more rapidly in the body to bring down glucose levels. Rapid and ultra-rapid insulins are also taken to correct high glucose levels when they occur or are still persistent a few hours after a meal.
Basal and prandial insulins are both analog insulins, meaning they are slightly different in structure from the insulin naturally produced in the body. Analog insulins have certain characteristics that can be helpful for people with diabetes. Human insulins, on the other hand, were developed first and are identical to those produced by the human body. Human insulins are classified as regular (short-acting insulin) or NPH (intermediate-acting). These are generally cheaper than analog insulins and can be bought without a prescription at some pharmacies.
Although many people use both basal and prandial insulin – which is called multiple daily injections of insulin (MDI) and consists of one or two injections of basal insulin each day as well as prandial insulin at meals – people with type 2 diabetes who are beginning insulin therapy may only need basal insulin to manage their glucose levels. Basal insulin requires fewer injections and generally causes less hypoglycemia. For these reasons, many healthcare professionals recommend basal insulin when you first start insulin therapy.
It is important to learn the different methods of taking insulin and what kinds of insulin can be delivered through each method. There are several ways to take insulin – syringe, pen, pump, or inhalation – though injection with a syringe is currently the most common for people with type 2 diabetes. There are many apps that can help you calculate your insulin doses.
Insulin pens are considered easier and more convenient to use than a vial and syringe. There are different brands and models of insulin pens available. Smart pens are becoming increasingly common and can help people manage insulin dosing and tracking. They connect to your smartphone and help you remember when you took your last dose, how much insulin you took, and when to take your next one.
Insulin pumps are attached to your body and can be programmed to administer rapid-acting insulin throughout the day, to cover both basal and prandial insulin needs. When you need to take insulin for meals or to correct high glucose, calculators inside the pump can help determine the correct dosage after you’ve programmed them with your personal insulin pump settings.
Inhaled insulin is ultra-rapid acting insulin and can replace insulin used for mealtime and corrections of high glucose. It is taken through an inhaler and works similarly to injected prandial insulin. People with diabetes who do not want to inject prandial insulin might use this, but it’s not for people who only use basal insulin. The only approved inhaled insulin on the market is the ultra-rapid-acting mealtime insulin Afrezza.
Your insulin regimen should be tailored to fit your needs and lifestyle. Adjusting your basal insulin dosage and timing will require conversations and frequent follow-up with your healthcare team. When initiating insulin therapy, you may be advised to start with a low dose and increase the dose in small amounts once or twice a week, based on your fasting glucose levels. People with diabetes should aim to spend as much time as possible with glucose levels between 70-180 mg/dl. Insulin may be used alone or in combination with oral glucose-lowering medications, such as metformin, SGLT-2 inhibitors, or GLP-1 agonists.
One of the most important things to consider is the characteristics of different insulin types. To learn more, read “Introducing the Many Types of Insulin – Is There a Better Option for You?” and discuss with your healthcare team.
In order to dose insulin to cover meals or snacks, you have to take a few factors into consideration. Your healthcare team should help you determine what to consider when calculating an insulin dose. Prandial insulin doses will usually be adjusted based on:
Current blood sugar levels. You’ll aim for a "target" blood sugar, and you should know your "sensitivity" per unit of insulin to correct high blood sugar levels.
Insulin sensitivity factor (ISF) or correction factor: how much one unit of insulin is expected to lower blood sugar. For example, if 1 unit of insulin will drop your blood sugar by 25 mg/dl, then your insulin sensitivity factor is 1:25. Your ISF may change throughout the day – for example, many people are more insulin resistant in the morning, which requires a stronger correction factor.
Carbohydrate intake. Insulin to carb ratios represent how many grams of carbohydrates are covered by one unit of insulin. You should calculate your carbohydrate consumptions for each meal.
Insulin to carbohydrate ratio: the number of grams of carbs “covered” by one unit of insulin. For example, a 1:10 insulin to carbohydrate ratio means one unit of insulin will cover every 10 grams of carbohydrates that you eat. For a meal with 30 grams of carbohydrates, a bolus calculator will recommend three units of insulin.
Physical activity. Adjust insulin doses before, and possibly after, exercise – learn more about managing glucose levels during exercise here.
Learning to adjust your own insulin doses may be overwhelming at first, especially given the many factors that affect your glucose levels. Identifying patterns in your glucose levels throughout the day may help you optimize the timing and dosing of your insulin. Your healthcare professional, a certified diabetes care and education specialist, or insulin pump trainer (if you use a pump), can help guide you through this process. Do not adjust your insulin doses without first talking to your healthcare team.
The frequency of testing will depend on your health status and activities during the day. Initially, you may be advised to check your blood glucose three to four times a day. As a starting point, check in with your healthcare team about how often to check your blood sugar. Many people test before meals, exercise, bedtime, and one to two hours after meals to ensure that they bolused their insulin correctly. Over time, your fasting, pre-meal, and post-meal blood glucose levels will help you figure out how to adjust your insulin doses.
Continuous glucose monitors (CGM) are particularly useful for tracking changes in glucose levels throughout the day. Some CGM devices also connect with an insulin pump to automatically adjust insulin delivery. After you start a treatment plan, the goal for most people is to spend as much time as possible in their target range. Talk with your healthcare professional about starting CGM and developing glucose targets.
It’s common to experience minimal discomfort from needle injections or skin changes at the insulin injection site. You may also experience side effects of insulin therapy, which can include some weight gain and hypoglycemia. In some people, insulin increases appetite and stops the loss of glucose (and calories) in the urine, which can lead to weight gain. Hypoglycemia can occur if you are not taking the right amount of insulin to cover your carb intake, over-correcting high glucose levels, exercising, or consuming alcohol. Treating hypoglycemia also adds more calories to your daily intake and can further contribute to weight gain. Contact your healthcare professional to adjust your insulin dose if you are experiencing hypoglycemia, or call 911 if you experience more serious side effects, such as severe low blood sugar levels, serious allergic reactions, swelling, or shortness of breath.
Staying in contact with your healthcare team is the best way to make the transition to insulin therapy. Though the first few days or weeks will be challenging, with the right support, you’ll find a diabetes care plan that works for you.
If you were recently diagnosed with type 2 diabetes, check out more resources here.