Insulin Therapy for Type 2 Diabetes

When you have type 1 diabetes, your pancreas doesn't make insulin, a hormone that moves sugar (glucose) from your bloodstream into your cells. People with type 1 diabetes need to take insulin throughout their lives to manage their blood sugar.

Type 2 diabetes is different. Your pancreas still makes insulin, but it doesn't move glucose into your cells as well as it should.

In the early stages of type 2 diabetes, you may try diet and exercise to lower your blood sugar. Your doctor can also prescribe drugs like metformin (Fortamet, Glucophage, Glucophage XR) or sulfonylureas such as glipizide (Glucotrol) or glyburide (Diabeta, Micronase). These drugs lower your blood sugar by keeping your liver from making glucose or helping your pancreas release more insulin.

Another option is for you to take insulin. Because type 2 diabetes progresses over time, most people with it eventually will need insulin.

When to Take Insulin

Good blood sugar control is important because it helps you avoid complications like vision loss, nerve and kidney damage, and heart disease.

In the past, your doctor might have put you on insulin only if oral drugs like metformin and lifestyle changes like diet and exercise didn't lower your blood sugar level enough. Now you might take insulin sooner after you're diagnosed. Research says insulin may help you control your diabetes better. It might also help your pancreas make its own insulin longer.

The advantage of insulin is it lowers blood sugar better than the oral drugs. Insulin also allows for more flexible dosing. Your doctor can tweak your dose to meet your precise blood sugar goals.

Your doctor will check your blood sugar control with an A1c test. This blood test measures your average blood sugar level during the past 2 or 3 months. The goal A1c for someone with type 2 diabetes is less than 7%.

You might take insulin for type 2 diabetes because:

You need to control your blood sugar for a short time. You may need insulin to treat temporary high blood sugar because of things like:


Lifestyle changes and pills haven't helped. If you've tried diet, exercise, and an oral diabetes drug and your blood sugar is still high, your doctor might prescribe insulin.

Your current treatment doesn’t work anymore. Over time, diabetes damages the cells in your pancreas that make insulin. Weight gain and chronic stress can speed this damage and make your body less responsive to insulin. Your pancreas may pump out more insulin at first, but eventually it won't be able to keep up with your body's demand for this hormone.

You haven't stuck with your treatment. Diet, exercise, and oral medicines will control your diabetes only if you use them. Missed doses and dietary lapses could derail your blood sugar control to the point where you need insulin.

Insulin Side Effects

The most common one is low blood sugar (your doctor may call it hypoglycemia), which causes symptoms like:

The needle may irritate your skin in the place where you inject. Insulin can also cause weight gain when you first start to take it.

Who Shouldn't Take Insulin

Insulin isn't right for everyone with type 2 diabetes. The weight gain it can cause could be a problem for people who are already very overweight or obese. To take insulin, you'll need to be able to give yourself shots or have someone close by who can do it for you. If you're afraid of needles, this may not be a good choice for you.

You may not be able to take insulin if you have kidney damage. Your body won't be able to remove the drug quickly enough to keep it from building up.

Your Insulin Treatment Plan

Your doctor will set a dose and schedule based on things like:

  • Your weight
  • Your blood sugar levels
  • Other health problems you have
  • How well the drug works
  • Whether you feel comfortable giving yourself a shot
  • The cost of the medicine

There are a few types of insulin, based on how long it takes to start working and how long it lowers your blood sugar.


When you first find out you have diabetes, your doctor may put you on a long-acting dose of basal insulin, which keeps your blood sugar levels steady throughout the day. You'll take it at dinnertime, bedtime, or in the morning. One shot of basal insulin a day may be enough to control your blood sugar.

If one dose isn't enough, you may need to add bolus insulin to help your body absorb sugar from food. You'll take a bolus dose 15 to 30 minutes before meals. Your doctor might have you combine insulin with oral diabetes drugs to lower your blood sugar better.

It's important to watch your diet, exercise, and take insulin and other medicines just as your doctor prescribed. If you're nervous about injecting, ask your doctor to show you less painful tools and techniques.

While you're on insulin, check your blood sugar level often. Your numbers will let your doctor know that you're taking the right insulin dose, and adjust it if you're not.

Length of Treatment

It depends on your situation.

If you just found out you have type 2 diabetes, you may need insulin for only a short time. Once your insulin levels are back to normal, you may be able to maintain them with diet and exercise, or with oral diabetes medicines.

If you've had diabetes for many years and your pancreas no longer makes enough insulin, you may need to stay on your treatment longer.

WebMD Medical Reference Reviewed by Michael Dansinger, MD on September 09, 2019



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Clinical Diabetes: "Clarifying the role of insulin in type 2 diabetes management."

Diabetes Care: "7. Approaches to glycemic treatment," "Insulin therapy in people with type 2 diabetes: Opportunities and challenges?"

Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy: "Drug treatment of type 2 diabetes mellitus in patients for whom metformin is contraindicated."

Diabetes UK: "Diabetes: The basics," "What is a hypo?"

Joslin Diabetes Center: "Sulfonylurea Agents: Oral Hypoglycemic Agents," "The truth about insulin and type 2 diabetes."

Mayo Clinic: "Diabetic ketoacidosis," "Type 1 diabetes."

Medscape: "Initiating insulin in the type 2 diabetes patient."

UpToDate: "Patient Education: Type 2 Diabetes: Insulin Treatment (Beyond the Basics)."

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