Diabetes Type 1

What is type 1 diabetes?

Diabetes is a chronic illness where the pancreas produces either no or less insulin, a crucial hormone that controls blood sugar. This condition subsequently leads to hyperglycemia. If it is not adequately handled as time goes by, it will cause severe damage to the body’s system, specifically nerves and blood vessels.1 The incidence of the disease itself varies and tends to increase annually. For instance, from 2000 - 2016, there was a 5% rise in premature mortality rate (i.e. below 70 years of age) due to diabetes. Moreover, according to the World Health Organisation, 8.5% of individuals over 18 years old were diagnosed with diabetes worldwide in 2014. In 2019, diabetes became the direct cause of 1.5 million deaths, with nearly half of the deaths happening prematurely.1

There are two types of diabetes; type 1 diabetes and type 2 diabetes. This paper will focus on type 1 diabetes, also known as insulin-dependent, juvenile, or childhood-onset diabetes. In type 1 diabetes, the body cannot make a hormone called insulin, causing dependency on a daily insulin injection or pump.2 In 2017, 9 million people were diagnosed with type 1 diabetes, with most cases occurring in high-income countries.1 Globally, type 1 diabetes comprises only 10% of diabetes cases; however, the incidence and prevalence increase annually.3

Causes and risk factors of type 1 diabetes 

The human body normally breaks down carbohydrates (macronutrients found in foods and beverages) into glucose. The amount and kind of carbohydrates an individual consumes can affect the blood glucose levels. Normally, the body controls the levels of glucose in the bloodstream and cells via two hormones: insulin and glucagon. Insulin is produced and secreted by beta cells in the pancreas which detect and respond to the excess of glucose in the bloodstream. Insulin acts to decrease the amount of glucose in the bloodstream by acting as a ‘gatekeeper’ allowing the glucose to be transported from the blood to the cell. Thus, the beta cells will send insulin to control the excess of glucose in blood, which usually occurs after a meal. However, this normal process does not happen in people diagnosed with type 1 diabetes.2

In type 1 diabetes, the body is struggling to move glucose from the bloodstream to the cells, where glucose is used to create energy for a cell to function. This means that glucose is trapped in the bloodstream causing high levels of glucose in blood and not enough glucose in cells causing them to starve for energy. Although type 1 diabetes is an autoimmune disorder, the risk factors include genetics, infectious agents, diet, exposure to toxic chemical compounds, metabolic problems, psychosocial and socioeconomic factors, among others.4 The chances of an individual in general population having a family history of type 1 diabetes is 1 in 30. However, the risks differ within a family: in maternal offspring, there is a 1 in 40 chance of developing type 1 diabetes, while in paternal offspring, it is 1 in 15. Furthermore, siblings have a 1:12 - 1:35 ratio of having type 1 diabetes, and the chances for identical siblings and monozygotic twins are 1:4 and 1:3 ratios respectively.4

A number of viruses have been associated with type 1 diabetes; however, more studies are needed to better understand the complex relationship between viral infections and type 1 diabetes. Previous literature has proposed that there is a connection between islet autoimmunity (production of autoantibodies to insulin antigens), viruses and type 1 diabetes. The footprints of viral infection might trigger the islet autoimmunity that might be difficult to discover due to the long incubation period, but it may subsequently progress into autoimmune diabetes. Another factor that can trigger islet autoimmunity and further progression of islet autoimmunity into type 1 diabetes is one’s diet. Toxic materials found in the environment or in food might also trigger the autoimmune mechanism in individuals that are genetically vulnerable, which subsequently causes the death of pancreatic islet cells and development of diabetes.4 

Surprisingly, not only the genetic and health aspects affect one’s risk of developing type 1 diabetes, but socioeconomic status (SES) is also one of the risk factors for type 1 diabetes. A study was conducted to figure out the association between SES and type 1 diabetes and the results were significant; there was an increase in diabetic retinopathy as the complication occurred since the people with the low SES do not control their diabetes routinely.6

Genetics and type 1 diabetes

Signs and symptoms of type 1 diabetes 

Type 1 diabetes symptoms commonly start from mild symptoms then gradually worsen over time and become more intense over several days, weeks, or months as the insulin is not being produced by the pancreas. The symptoms in children and adults include excessive thirst and hunger, unexplained weight loss, blurred eyesight, slow healing of cuts and bruises, fatigue, vaginal yeast infection, and frequent urination 7.

There will be complications like diabetic ketoacidosis (DKA) followed up if the diagnosis is delayed. To recognize this complication, there are also symptoms such as fruity-smelling breath, nausea and vomiting, stomach pain, rapid breathing, confusion, drowsiness, and loss of consciousness 7.  

Difference between type 1 and type 2 diabetes

Type 1 diabetes is slightly different from type 2 diabetes although both of them are categorized as diabetes mellitus that cause hyperglycemia. The major difference between these types of diabetes is the insulin production. In type 1 diabetes, the insulin is not adequately produced by the pancreas; whereas, in type 2, the insulin is produced by the pancreas but at a low level due to insulin resistance. Furthermore, type 2 diabetes is usually caused by lifestyle aspects such as obesity and a sedentary lifestyle, while type 1 diabetes is caused by an autoimmune reaction. Type 2 diabetes is more common in older adults, but can also develop in children. However, type 1 diabetes tends to develop in young adults, although it could still happen at any age 7.

Type 1 diabetes is often associated with increased ketone levels upon diagnosis, whereas type 2 diabetes is associated with increased blood pressure and/or cholesterol levels. The therapy for these illnesses is also different: type 1 diabetes is treated with continuous insulin administration, while type 2 diabetes treatment includes medications that control blood sugar levels and could occasionally be changed or stopped. 8 

Blood sugar testing


Type 1 diabetes management is complex due to the factors that affect the blood sugar levels, but there are three major components of type 1 diabetes management -  insulin, blood sugar monitoring, and carbohydrate counting. 7 

Insulin therapy varies since there are several kinds of synthetic insulin that work at different speeds and vary with how long they stay in the body. The dose of insulin also depends on several factors, such as body weight, age, physical activity level, diet, and any given blood sugar level. A specific amount of insulin should be given during meal time to fix the high blood sugar levels along with the insulin background level. 7

Insulin injection

Before performing the injection, an individual should prepare an insulin pen, a new pen needle, and a disposal box for the unused needles. Furthermore, an individual needs to know the dosage to be injected.9,10 The injection dosage depends on the brand of the insulin and personalized GP prescription. One should pay attention to the length of time before the insulin starts to work (onset), the time when the insulin works maximally to decrease the blood sugar (peak) as well as the duration of insulin’s work before the effect disappears (duration).9


Insulin glulisine (Apidra®)

  • Onset: 5-15 minutes
  • Peak: 1-3 hours
  • Duration: 3-5 hours

Insulin aspart (Novolog®)

  • Onset: 10-15 minutes
  • Peak: 1-3 hours
  • Duration: 3-5 hours

Insulin lispro U-100/U-200 (Humalog®)

  • Onset: 10-15 minutes
  • Peak: 1-3 hours
  • Duration: 3-5 hours

Regular insulin (Novolin R, Humulin R)

  • Onset: 30-60 minutes
  • Peak: 2-4 hours
  • Duration: 5-8 hours

NPH insulin (Novolin N, Humulin N)

  • Onset: 1-2 hours
  • Peak: 4-12 hours
  • Duration: 14-24 hours

Insulin detemir (Levemir®)

  • Onset: 1 hour
  • Peak: 3-14 hours
  • Duration: Up to 24 hours

Insulin U-100 (Lantus®, Basaglar®)

  • Onset: 3-4 hours
  • Peak: No peak
  • Duration: Up to 24 hours

Insulin glargine U-300 (Toujeo®)

  • Onset: 6 hours
  • Peak: No peak
  • Duration: Up to 36 hours

Insulin degludec U-100/U-200 (Tresiba®)

  • Onset: 1 hour
  • Peak: No peak
  • Duration: Up to 42 hours

Pre-mixed insulin

  • Onset: 70/30 (70% N and 30% R)
  • Peak: 0.5-1 hour
  • Duration: 2-12 hours / 10-16 hours

50/50 (50% N and 50% R)

  • Onset: 0.5-1 hour
  • Peak: 2-12 hours
  • Duration: 10-16 hours

Pre-mixed insulin

  • Onset: Humalog® mix 75/25 (75% NPL and 25% insulin lispro)
  • Peak: 5-20 minutes
  • Duration: 1-2 hours / 10-16 hours

Humalog® mix 50/50 (50% insulin lispro protamine and 50% insulin lispro)

  • Onset: 5-20 minutes
  • Peak: 1-2 hours
  • Duration: 10-16 hours

NovoLog® mix 70/30 (70% insulin aspart protamine and 30% insulin aspart)

  • Onset: 5-20 minutes
  • Peak: 1-2 hours
  • Duration: 10-16 hours

How to inject insulin

The insulin can be injected in the legs, stomach, back of arms and buttocks. It is important to consider comfort as injections to certain body parts can have side effects, including local pain and  allergy reaction.9

How to store insulin injection

Insulin is  temperature-sensitive, therefore, once received, it should be stored in the refrigerator (approximately 36℉ - 46℉ or 2.2℃ - 7.7℃), and it must be used within 28 days after opening.11


Unfortunately, type 1 diabetes is unpreventable. Currently, all treatments are directed to managing the blood glucose levels via diet, lifestyle changes and insulin administration, in order to prevent further complications. It is also highly advised to perform regular blood glucose checks to track the disease severity, and do a family history screening of autoantibodies that trigger diabetes. It is hoped that by doing the screening, people can detect type 1 diabetes in the earliest phases and manage it accordingly.


Poor management of type 1 diabetes can lead to several health complications. Continuous high blood sugar can result in diabetic retinopathy, diabetic macular edema, glaucoma, cataract, gangrenes, heart disease, high blood pressure, kidney and oral health problems, nerve damage, dry skin, bacterial and fungal infection, diabetic dermopathy as well as stroke.7

Living with type 1 diabetes 

Having type 1 diabetes needs complex daily management and planning, as blood sugar needs to be regularly checked with a glucometer or Continuous Glucose Monitor (CGM). It is important to check it before and after meals as well as before sleep followed by the insulin therapy and other medications. It is crucial to keep everything under control including the body’s health; therefore, GP and specialists such as endocrinologists and ophthalmologists visitation are needed. Furthermore, receiving mental support is as important as medical. 7

Recent research in type 1 diabetes

There is a new innovation in type 1 diabetes therapy, named immunotherapy. This therapy is set up to reprogramme the immune system not to attack the insulin-producing beta cells in the pancreas. However, more research is necessary to evaluate the use of immunotherapy in type 1 diabetes.12  


Type 1 diabetes is an autoimmune disease caused by the failure of beta cells in the pancreas to produce and secrete the insulin hormone that regulates blood glucose levels. The symptoms emerge once the illness has significantly progressed, explaining why some people experience the sudden onset of symptoms which then gradually worsen over time. Currently, the sole therapy for type 1 diabetes is continuous insulin administration in the form of injections or pumps. There is no way to prevent this illness but there is a way to prevent its complications: by routinely contacting the GP and specialists, properly taking medications and insulin injections, as well as reaching out to the community to gain more knowledge about the disease and receive support.

Dwi Tampubolon

Masters of Science - MSc Global Health Policy Student, The University of Edinburgh, Scotland

Dwi is a Research Assistant of Radiology Consultant and a Medical Writer.

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