Introduction

This article will introduce how insulin therapy is used to manage blood sugar levels in people with diabetes. 

Understanding diabetes

Diabetes (or diabetes mellitus) is a condition that causes your blood sugar (glucose) level to become too high.¹ 

Your body produces a hormone, called insulin, to stop your blood glucose levels from getting too high. However, in diabetes, this is not produced or does not work as it is supposed to.¹

Types of diabetes

There are two types of diabetes: 

• Type 1 diabetes occurs when your body attacks the cells responsible for producing insulin, so you do not produce enough. It is a lifelong condition. 
• Type 2 diabetes occurs when your body fails to produce enough, or does not respond to insulin properly¹

Type 2 diabetes is much more common than type 1 diabetes. 

Role of insulin in the body

Insulin is a hormone released from a gland found behind the stomach, called the pancreas. It works as follows:² 

1. When you eat, glucose molecules from the food are digested and absorbed into your bloodstream. 
2. The increase in blood glucose levels stimulates the release of insulin from the pancreas. 
3. Insulin then directs specific cells in your liver, muscles and fat to take up glucose and store it. 
4. Taking glucose out of the bloodstream and into other cells for storage brings blood glucose levels back down to normal. 

However, in diabetes, not enough insulin is produced, or it does not work properly, so blood glucose levels are not returned to normal. This means people with diabetes have persistently high blood glucose levels.¹ 

What is insulin therapy?

To manage diabetes, certain individuals use insulin therapy to help control their blood glucose levels. This involves giving insulin to replace that which is not made by their body.³ 

People with type 1 diabetes will always be given insulin therapy as they cannot produce any insulin. People with type 2 diabetes will sometimes be given insulin therapy, but not always, depending on the severity of their condition. 

Basics of insulin therapy

Types of insulin therapy

This section will outline the different types of insulin therapy and their usage. 

Rapid-acting

Rapid-acting insulins include insulin lispro (Admelog, Humalog, and Lyumjev), insulin glulisine (Apidra), and insulin aspart (Fiasp, NovoRapid and Trurapi). It is often referred to as “mealtime” or “bolus” insulin. Rapid-acting insulin is taken just before meals to prevent a spike in blood sugars after eating. It works very quickly, taking effect after just 10-20 minutes and can last up to 5 hours.³

Short-acting

Short-acting insulins include the brand names Actrapid and Humulin S. It is also called Regular or Neutral insulin, and often referred to as "mealtime” or “bolus” insulin.³ Short-acting insulin is taken just before meals to prevent a spike in blood sugars after eating. It acts quickly after around 30-60 minutes, and lasts up to 8 hours.³

Intermediate-acting

Intermediate-acting insulins include the brand names Humulin I and Insulatard. It may be referred to as “isophane insulin”. Intermediate-acting insulins are injected once or twice a day to provide a continuous low level of insulin (or basal level). It starts to work after 1-2 hours and lasts between 11-24 hours.⁴

Long-acting

Long-acting insulins include insulin detemir (Levemir), insulin glargine (Abasaglar, Lantus, Semglee, and Toujeo), and insulin degludec (Tresiba). Long-acting insulin provides a continuous low level of insulin to manage glucose levels. Insulin detemir is given twice a day, and insulin glargine and insulin degludec are given once a day. It works after 30 minutes up to 4 hours, and lasts between 16-24 hours.^3,4

Methods of insulin administration

Insulin can be given in different ways. The list below provides some examples:

• Insulin pen - usually painless as the needle is small and injects just under the skin surface
• Insulin syringes - used less often with specific types of insulin
• Insulin pumps - attached to your skin to continuously provide insulin into the body through a small tube⁵

Importance of consistent dosing and timing

It is important to monitor your blood glucose and take your insulin at the right dose and time. You will be advised by your healthcare professional on how to adjust your doses depending on your blood glucose levels. 

Inconsistent insulin dosing can lead to very low blood glucose levels, known as hypoglycaemia or “hypos”.⁶ Episodes of hypoglycaemia can be dangerous if not treated quickly, so speak to your healthcare professional, or refer to the NHS website, if you are unaware of how to manage them. 

Meal planning for diabetes

People with diabetes should use meal planning to help manage their blood glucose levels. 

Importance of balanced meals

Balanced meals are very important for individuals with diabetes. A balanced meal plan will look different for every individual and will be designed depending on your needs.⁷

Several factors can be managed with a good meal plan. These include:

• Managing or achieving weight goals
• Maintaining blood sugar and blood fat levels, including glucose and cholesterol
• Maintaining blood pressure goals 
• Reducing the complications of diabetes 

Carbohydrate counting and its role in meal planning

Individuals with diabetes may consider carbohydrate counting to manage blood glucose levels.⁷

The American Diabetes Association 2019 guidelines suggest that individuals with diabetes incorporate nutrient-dense and high-fibre carbohydrates into their diet. For example, fruits and vegetables, whole grains, and dairy products. The guidelines recommend that individuals with diabetes avoid consuming sugar-sweetened drinks, including fruit juices.

However, a diet low in carbohydrates is not recommended for everyone and some individuals, including pregnant women and those with kidney disease, should not follow a low-carbohydrate diet. If you are unsure, speak to your healthcare professional. 

Incorporating proteins, fats, and fibre

Including more protein in your diet may help you feel “fuller for longer,” however, it does not necessarily impact blood glucose levels. Try to incorporate lean animal meats, nuts or plant protein to supplement a balanced meal. However, be aware of high salt content in plant proteins.⁷

Different types of fats can be found in the diet - some are healthier, and others are unhealthier. In general, it is recommended that nut butters, olive, vegetable, and rapeseed oils and spreads are prioritised. 

A fibre-rich diet is recommended by the American Diabetes Association for individuals with diabetes. This includes incorporating whole grain breads and cereals, fruits and vegetables, and legumes and pulses. Fibre-rich foods are digested more slowly, which helps manage blood glucose levels and weight. 

For more guidance, Diabetes UK provides a summary of a balanced diet for individuals with diabetes. 

Impact of food choices on blood glucose levels

To avoid raising blood glucose levels quickly, avoid processed foods high in sugar, fat and salt. Instead, think about nutrient-dense carbohydrates and balancing this with protein, healthy fats and fibre.⁷

Coordination of insulin therapy and meal planning

Your healthcare professional will provide personalised advice on how to coordinate insulin therapy and meal planning. They may provide advice on matching insulin doses to meal content, adjusting insulin before a meal, and the timing of insulin doses. 

Practical tips for success

Regular monitoring of blood glucose levels

As an individual on insulin therapy, it is important to regularly monitor your blood glucose. This will tell you how good your insulin management is, if any adjustments need to be made, and keep you aware of “hypos”. At home, you may monitor your blood glucose with a finger-prick test.⁸

Consulting with a healthcare professional for personalised guidance

As every individual with diabetes has different needs, it is important that you talk with your healthcare professional to work out what is best for you. 

Incorporating physical activity into daily routine

Incorporating exercise into your daily routine is important to help manage your diabetes. Exercise can help lower blood glucose levels; however, too much exercise without insulin adjustment may risk “hypos”. Speak to your healthcare professional for personalised advice.⁹

Being flexible and making adjustments as needed

For individuals with diabetes, it is good to be flexible and adjust their routine as needed. With time, this will become easier, and your healthcare professional will provide advice for this. 

Summary

Diabetes is a condition which causes blood sugar, or glucose, levels to get too high. There are two types of diabetes, which differ in how they arise. Insulin therapy is used to treat patients with type 1 diabetes and sometimes in those with type 2 diabetes. There are various forms of insulin therapy, with different speeds of action and methods of delivery. Your healthcare professional will provide a personalised insulin therapy plan for you. It is also important to have a balanced meal plan, including nutrient-dense carbohydrates, proteins, healthy fats, and fibre.