What is type 1 diabetes?

Type 1 diabetes (T1D) is a chronic disease in which your pancreas doesn’t make enough insulin.¹ Insulin is a protein hormone that maintains normal blood glucose levels by promoting the uptake and usage of glucose by your cells, adjusting carbohydrate metabolism, and promoting cell division and growth. Without insulin, glucose isn’t absorbed or used properly, and instead accumulates in the blood. As such, T1D causes your blood glucose (blood sugar) levels to become abnormal, potentially causing fatigue, excessive hunger or thirst, weakness, and blurred vision.

The NHS outlines that patients with T1D need to take insulin every day to keep their blood sugar levels under control.² There is no age or weight limitation for this disease, and anyone can develop it. However, individuals with a family history of diabetes are at an increased risk.

What causes type 1 diabetes?

The causes of T1D are not yet fully understood, but scientists think it is triggered by a combination of genetic and environmental factors.³ Studies have found that T1D is likely an autoimmune disorder (meaning that the body attacks itself by mistake). In autoimmune conditions, your immune system cannot tell the difference between your own and foreign cells. To protect you from any possible bacterial or viral infections, your T-cells (immune cells) mistakenly attack and destroy healthy beta cells in the pancreas⁴. Beta cells play an important role in making insulin to balance blood sugar levels, so this process leads to insulin deficiency.

It may be too abstract to explain the autoimmune process leading to insulin deficiency, but thinking of it this way, if we see the pancreas as a factory, the beta cells as the employees who produce the products (insulin), and the immune cells as the security team. Usually, immune cells use antigens (‘bad’ cell markers) to help identify which cells are friends and are enemies. Whilst producing insulin, beta cells produce antibodies (‘good’ cell markers) that cover their surface. In an autoimmune disorder, the immune cells misinterpret these ‘good’ cell markers and assume they are bad. This gives security a signal that all employees in this factory are potential enemies - so if they continue to produce insulin, they will be targeted and killed. 

Is insulin deficiency serious?

Insulin deficiency can cause serious problems, such as:⁵

• Increased urination: without insulin, blood sugar is unable to enter cells and builds up in the bloodstream before being excreted in the urine. Increased urination also decreases levels of salt and water in the blood, which is why diabetes patients often feel thirsty.
• High blood sugar: insulin helps control the use and storage of glucose in the blood. 
• Diabetic ketoacidosis (DKA): DKA is a life-threatening disease. Without enough insulin, the body cannot use blood sugar to convert fat into the energy it needs. In response to this, the body uses lipase hormones to break down fat for energy. This releases a large amount of fatty acids which oxidise ketones in the liver.

Insulin deficiency can also cause symptoms such as:

• Vomiting
• Low blood pressure
• Infections
• Impaired conscious level
• Weight loss, tiredness 

Treating type 1 diabetes

Currently, the most commonly used treatment for patients with type 1 diabetes is insulin therapy. It is usually taken by injection.

The goal of insulin therapy is to remedy the lack of insulin in the body, keep your blood sugar within your target range, and prevent long-term complications of diabetes.⁶ If you have type 1 diabetes, you may need to inject insulin often to stay healthy.

Types of insulin therapy 

There are various insulin therapies used to treat diabetes. Insulin is grouped by how fast and how long it works in your body.⁷

• Onset – How fast it works or lowers your blood sugar
• Peak time – When the effect of the injected insulin has its maximum effect 
• Duration – How long does the effect of insulin last

A fast-acting insulin therapy, also known as bolus insulin, should always be taken before or after meals. These include:

• Rapid-acting insulin: works within 15 minutes, reaches its peak efficiency within one hour, and lasts between 2 to 4 hours (depending on the brands used). It is usually taken after meals.
• Short-acting insulin: works within 30 minutes, reaches its peak efficiency between 2 to 3 hours after injection, and lasts about 3 to 6 hours. This insulin is usually taken 30 to 60 minutes before a meal.

A slower-acting insulin therapy, also known as background insulin, is often injected once or twice daily. These include:

• Intermediate-acting insulin: works within 2 to 4 hours, reaches its peak efficiency around 4 to 12 hours after injection, and lasts between 12 to 18 hours. This insulin covers the needs for half a day or overnight. It is often combined with rapid- or short-acting insulin. 
• Long-acting insulin: works within 2 hours, and does not have a peak efficiency time. It can last up to 24 hours and cover the needs for a full day. It is often combined with rapid- or short-acting insulin.

Some patients may be prescribed just one type of insulin therapy which combines fast-acting and slower-acting insulin. This is called mixed insulin. These combination insulin products work within 5 to 60 minutes, but the time taken for them to reach their peak efficiency varies between individuals. They usually last between 10 and 16 hours.

Some types of insulin look clear, while others are cloudy. The cloudy insulin contains ingredients that can slow down the rate it is absorbed into your body. Check with your doctor or GP whether the insulin you are taking should be clear or cloudy. If the insulin you use should be clear but it is cloudy, do not use it. 

How to use insulin therapy

Insulin therapy is usually injected by syringes, insulin pens, or insulin pumps.⁸

Insulin syringes

There are three different sizes of syringes: 30-unit (0.3 ml), 50-unit (0.5 ml) and 100-unit (1.0 ml) measures. These measures refer to how much insulin dosage it needs to hold. For example, you can measure a 10-unit dose in a 30-unit syringe.

Insulin pens

It is much easier to use insulin pens than syringes. There are disposable and reusable insulin pens. Disposable pens are prefilled with insulin and thrown away after the insulin cartridge is empty. Reusable pens use insulin cartridges that can be replaced.

Insulin pumps

An insulin pump is a small programmable device that regularly releases insulin to your body. Insulin pumps can be 'tethered' by a fine tube linking the pump to the cannula, with the pump usually stored in a pocket or clipped on a belt. Another type of  Insulin pump can be patched onto your arm or shoulder. This is known as a micro pump which has no tube or a very short tube.

Insulin pumps are not suitable for everyone - so you should let your doctor know if you would prefer to use one.

Side effects associated with insulin therapy

Insulin therapy may cause:⁹

• Low blood sugar symptoms
• Feeling dizzy or hungry
• Sweating
• Shaking
• Anxiety
• Weight gain

Summary

Type 1 diabetes is an autoimmune disease that is characterised by immune cells attacking the pancreatic beta cells responsible for producing insulin. Type 1 diabetes causes insulin deficiency and leads to abnormal blood sugar levels. Patients with type 1 diabetes may require lifelong insulin therapy to maintain normal blood sugar levels. Insulin therapy is usually administered by manual injections, but it also can be taken using a smart electronic pump device patched on your skin. If your insulin therapy should be clear, but looks cloudy, don’t use it. Better to consult with your GP or healthcare professionals if you overdosed by mistake.

FAQs

How do I know if I have type 1 diabetes?

Patients with type 1 diabetes usually feel very thirsty and tired and may experience weight loss or blurred vision. If you think you have diabetes, you should book an appointment with your GP as soon as possible.

Why does insulin deficiency increase urination?

Insulin helps blood sugar enter your cells. If you are lacking in insulin, a high amount of blood sugar will be left in your blood and excreted through more urine - simultaneously increasing the amount of water and salt lost in your urine. 

Which type of insulin therapy is best?

There is no ‘best’ insulin therapy besides the one that is best for you. Consult with your diabetes healthcare team to see which insulin therapy will suit you better.