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Expert-reviewed by Ashwini S.Kanade, Registered Dietician and Certified Diabetes Educator with 17 years of experience
Fact-checked by Aditya Nar, B.Pharm, MSc. Public Health and Health Economics

Whether you’re newly diagnosed with diabetes or have been coping with it for some years, the best way to manage it is to be properly informed about what the treatment involves. While most people are aware of the role of insulin in diabetes, many don’t know about it beyond basic information.

So, what are some of the important details that every person with diabetes should know about insulin? Let’s find out.

What is insulin?

The carbohydrates in the food you eat are broken down into glucose by your digestive system. Insulin, a hormone produced by your pancreas, helps in absorbing this glucose and regulates carbohydrate and fat metabolism in your body.

In type 1 diabetes, the body does not produce insulin, while in type 2 diabetes, the body either does not produce enough or is unable to effectively use the insulin it does produce. Insulin medication is, therefore, an inevitable part of the treatment in most cases.

Who needs external administration of insulin?

When your body fails to produce enough, insulin, the medicated form is used to replenish it. In most cases, doctors will advise insulin therapy if:

  • You have type 1 diabetes,
  • You have uncontrolled type 2 diabetes,[1]
  • Your diet, exercise and oral medications are failing to achieve adequate sugar control,[2]
  • You have type 1 or type 2 diabetics, and become pregnant,[2]
  • You have type 1 or type 2 diabetes, and are undergoing an operation. [3]

Why do type 2 diabetics need insulin?

Generally, a step-wise introduction of different oral medications over the years, along with healthy eating and exercise, is used to manage type 2 diabetes.

Treatment usually begins with a single oral drug to control blood sugar levels. If uncontrolled diabetes still persists or if the drug stops having the desired effect over time, the next step is to take a combination of oral drugs, which can work more efficiently.

Type 2 diabetics need insulin therapy when oral medication, diet, and exercise aren’t enough to control their blood sugar.[4]

But insulin is no longer used only as the last step. In fact, recent treatment guidelines recommend that the earlier people with type 2 diabetes start taking insulin, the better. If you have been newly diagnosed with type 2 diabetes, your doctor may advise insulin therapy if you:[2]

  • have symptoms of high sugar like excessive thirst (polydipsia), passing abnormally large amounts of urine (polyuria), etc.
  • and/or have Glycosylated Haemoglobin (HbA1c) > 10%
  • and/or very high blood glucose levels (> 300 mg/d)

A study conducted by Weng J, et al., shows that early intensive insulin therapy in newly diagnosed type 2 diabetics can not only help restore the function of the pancreas but also result in prolonged diabetes remission.[5]

How does insulin therapy help?

The insulin released from your pancreas keeps your blood sugar in the normal range. Your body’s response to sugar levels is automatic. It releases a low, background level of insulin (basal insulin) throughout the day to maintain blood sugar levels overnight and between meals. When you eat, it produces a quick burst of insulin (bolus insulin) in response to the sugar absorbed from your meal.

Insulin taken through injections or an insulin pump has almost the same effect as natural insulin. It estimates normal insulin levels and helps lower your high blood sugar. To achieve this, your insulin therapy may consist of:

  • Background replacement of basal insulin
  • Quick burst replacement with bolus insulin

Research shows that intensive insulin therapy is effective in delaying the onset and progression of diabetic complications of the eyes (retinopathy), kidneys (nephropathy), and nerves (neuropathy).[6]

Are there types of insulin?

There are five different types of insulin. They differ in how fast they act and how long their effects last:[7]

Rapid-acting insulin●     starts working in about 15 minutes

●     lasts for 3 to 5 hours

Short-acting insulin●     starts working in 30 to 60 minutes

●     lasts 5 to 8 hours

Intermediate-acting insulin●     starts working in 1 to 3 hours

●     lasts 12 to 16 hours

Long-acting insulin●     starts working in about 1 hour

●     lasts 20 to 26 hours

Premixed insulin●     combination of 2 types of insulin


Your doctor will recommend the best type of insulin for you depending on factors such as your age, body weight, sugar control, lifestyle, your preferred frequency of injections, and your response to insulin.

How is insulin administered?

The most common way of taking insulin is a syringe. You can inject the insulin into the fat layer under your skin. You can also use insulin pens and pumps.

Insulin pens deliver the hormone via a cartridge and a replaceable needle. You can adjust the dose and frequency according to your requirements. An insulin pump, on the other hand, is discreetly attached to your pocket, waistband, belt, or innerwear, and supplies a pre-programmed amount of insulin at a constant rate through a thin tube placed under your skin.

Are insulin injections painful?

The injections don’t hurt. Present day insulin injections use very tiny needles, making the prick nearly painless.

But your fear of insulin injections may arise from a condition called “psychological insulin resistance”.[8] In such cases, you may be reluctant to start taking insulin because you’re afraid of painful injections, low blood sugar, and weight gain. You may also link insulin therapy to the worsening of your condition, and resent it because you perceive it to be permanent, restrictive, and harder to follow.

Is there a way to take insulin without injections?

While injections are the most common way of administration, you can also use an insulin inhaler to breathe insulin powder through your mouth into the lungs.

Scientists are trying to develop insulin in tablet form. But this is still in the clinical trial stage.

How often should you take insulin?

Based on your requirements, your doctor will decide how often you need to take insulin. Generally, to keep your background insulin under control, you will need a basal insulin injection once or twice daily to provide a continuous, low level of insulin throughout the day. You can also use an insulin pump, which provides continuous infusion according to your body’s requirements. The bolus insulin should be timed according to your meals to cover the sugar in your food and should be taken before eating.

If you have type 1 diabetes, you may need multiple daily injections of bolus insulin along with a basal insulin dose or continuous insulin infusion under the skin. If you have type 2 diabetes, your insulin needs may range from one injection a day to multiple injections. You may need basal insulin replacement, or bolus insulin replacement, or both, or continuous infusion depending on your sugar control status.

Usually, insulin therapy is started by adding a dose of basal insulin to your existing oral medication regimen.

What’s the correct way of storing insulin?

Here are some of the tips for storing insulin properly:

  • Store unopened vials in the refrigerator until the expiration date.
  • Allow the vial to reach room temperature before injection.
  • Store opened vials at room temperature for approximately a month. Discard after that.
  • Do not store your insulin at extreme temperatures. Keep away from sunlight. Do not freeze.
  • Watch out for changes in colour, clarity and smell. Do not use the insulin if you notice any changes.
  • Don’t use insulin beyond its expiry date.

Find out if you are making any of these 5 mistakes while using insulin.

Are there any side effects of insulin therapy?

The side effects of insulin injections are uncommon. You may experience redness, swelling and itching or pain at the injection site. But these signs usually resolve in a few days. On rare occasions, you may have a severe allergic reaction.

Too much or too little insulin can have undesirable effects. While too much insulin can cause dangerously low blood sugar levels (hypoglycaemia), too little insulin can cause your blood sugar levels to be very high (hyperglycaemia).

You may gain weight if you are on insulin therapy.[9] Intensive insulin treatment can also cause a temporary worsening of your diabetic eye disease (diabetic retinopathy) if your long-standing sugar control has been poor.[10]

What precautions should you take?

It is important to keep certain things in mind when you are on insulin:

  • Use the right injection techniques, and administer the appropriate dose of insulin
  • Use disposable needles and syringes, and sterilise any reusable parts to avoid any risk of infection
  • Inject into a fresh, unused patch of skin for each dose
  • Watch out for signs of dangerously low blood sugar levels (hypoglycaemia)
  • Balance your insulin use, carbohydrate intake, and exercise. Be consistent with your carbohydrate intake. You may need to adjust the insulin dose with modifications in your diet and physical activity.
  • Alcohol intake may increase the risk of hypoglycaemia [11]
  • Inhaled insulin is not recommended if you have chronic lung diseases like asthma or chronic obstructive pulmonary disease [12]
  • Do not use inhaled insulin if you smoke or have recently stopped smoking [12]

Photo courtesy: Shutterstock


  1. Vinik A. Advancing therapy in type 2 diabetes mellitus with early, comprehensive progression from oral agents to insulin therapy. Clin Ther. 2007 Jun;29(6 Pt 1):1236-53. Review. PubMed PMID: 18036387.
  2. American Diabetes Association (ADA) 2017 Guidelines
  3. Husband DJ, Thai AC, Alberti KG. Management of diabetes during surgery with glucose-insulin-potassium infusion. Diabet Med. 1986 Jan;3(1):69-74. PubMed PMID: 2951140.
  4. Yki-Järvinen H, Esko N, Eero H, Marja-Riitta T. Clinical benefits and mechanisms of a sustained response to intermittent insulin therapy in type 2 diabetic patients with secondary drug failure. Am J Med. 1988 Feb;84(2):185-92. PubMed PMID: 3044067.
  5. Weng J, Li Y, Xu W, Shi L, Zhang Q, Zhu D, Hu Y, Zhou Z, Yan X, Tian H, Ran X, Luo Z, Xian J, Yan L, Li F, Zeng L, Chen Y, Yang L, Yan S, Liu J, Li M, Fu Z, Cheng H. Effect of intensive insulin therapy on beta-cell function and glycaemic control in patients with newly diagnosed type 2 diabetes: a multicentre randomised parallel-group trial. Lancet. 2008 May 24;371(9626):1753-60. doi: 10.1016/S0140-6736(08)60762-X. PubMed PMID: 18502299.
  6. Diabetes Control and Complications Trial Research Group, Nathan DM, Genuth S, Lachin J, Cleary P, Crofford O, Davis M, Rand L, Siebert C. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med. 1993 Sep 30;329(14):977-86. PubMed PMID: 8366922.
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  8. Swinnen SG, Hoekstra JB, DeVries JH. Insulin Therapy for Type 2 Diabetes. Diabetes Care. 2009;32(Suppl 2):S253-S259. doi:10.2337/dc09-S318.
  9. Russell-Jones D, Khan R. Insulin-associated weight gain in diabetes–causes, effects and coping strategies. Diabetes Obes Metab. 2007 Nov;9(6):799-812. Review. PubMed PMID: 17924864.
  10. Davis MD. Worsening of diabetic retinopathy after improvement of glycemic control. Arch Ophthalmol. 1998 Jul;116(7):931-2. PubMed PMID: 9682709.
  11. Arky RA, Veverbrants E, Abramson EA. Irreversible Hypoglycemia A Complication of Alcohol and Insulin. JAMA. 1968;206(3):575–578. doi:10.1001/jama.1968.03150030031006
  12. Ghosh S, Collier A. Inhaled insulins. Postgraduate Medical Journal. 2007;83(977):178-181. doi:10.1136/pgmj.2006.053868.

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Disclaimer: The information provided in this article is for patient awareness only. This has been written by qualified experts and scientifically validated by them. Wellthy or it’s partners/subsidiaries shall not be responsible for the content provided by these experts. This article is not a replacement for a doctor’s advice. Please always check with your doctor before trying anything suggested on this article/website.


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