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Diabetes: Symptoms, Causes & Complications

Diabetes is a common condition that affects millions of people around the world. Find out more about the symptoms, causes and complications of diabetes here.

What is diabetes?

Diabetes is a serious, chronic condition that affects millions of people around the world [1]. It is very common — an estimated 537 million adults worldwide have some form of diabetes [2], and new cases are increasing by an average of 3% each year [1].

Diabetes is a long-term condition that causes blood glucose levels to be raised [2]. The condition occurs when the pancreas cannot produce enough insulin, the hormone that lowers blood glucose, or when the body cannot effectively use the insulin [1].

There are different types of diabetes [3]. You can find out about the main types of diabetes — including causes, symptoms and treatments — below.

Type 1 diabetes

About 5–10% of people with diabetes have type 1 [3]. It is caused by the body’s immune system attacking and destroying cells in the pancreas [3], which means the body can’t produce enough (and most of the time, any) insulin [1, 2, 3].

The exact reason of type 1 diabetes currently isn’t known [1]. However, risk factors for developing type 1 include your family history, ethnicity and a history of certain viral infections in childhood [3]. The majority of type 1 diabetes occurs in children and adolescents [1]. At the moment there is no treatment that can prevent you from getting type 1 diabetes [1].

Every person is different, but there are some characteristic symptoms that are often present when type 1 diabetes starts. These can include excessive thirst and urination, weight loss, constant hunger, fatigue and vision changes [1].

People with type 1 diabetes need to take insulin every day to regulate the amount of glucose in their blood [1]. This is typically administered either as injections or as a continuous infusion under the skin, through insulin pump therapy (also known as CSII — continuous subcutaneous insulin infusion) [4]

Reaching blood glucose targets is very important in preventing and slowing the complications of diabetes [1]. If you are diagnosed with type 1 diabetes, your healthcare team will teach you about important concepts such as adapting your insulin dose to your carbohydrate intake, pre-meal blood glucose, and any anticipated activity that you might undertake [4].


Type 2 diabetes

Type 2 diabetes accounts for the majority of cases around the world [1] — almost 90% of diabetes cases worldwide are type 2 diabetes [5]. It is caused when the body becomes resistant to the effects of insulin, which cannot be overcome by producing more insulin [3].

At the beginning, type 2 diabetes often has no symptoms at all [1]. It develops slowly and there can often be a long period of time where the condition is undetected and undiagnosed [1]. Instead, some people may be diagnosed after contacting their healthcare team because of complications of the condition, such as problems with their heart or vision [1].

There are two types of risk factors for type 2 diabetes — those that cannot be changed and those that can be changed, such as lifestyle choices [3]. Risk factors that can’t be changed include:

  • Age [3]
  • Gender [2]
  • Ethnicity [3]
  • Family history of diabetes [3]
  • If you have had diabetes in pregnancy [3]
  • If you were born with a low birth weight [3]

Changeable and lifestyle risk factors for type 2 diabetes are [3]:

  • Increased body mass index (BMI)
  • Low physical activity
  • Poor nutrition
  • High blood pressure
  • Smoking
  • Alcohol use

Unlike type 1 diabetes, there are effective ways to prevent type 2 diabetes [1]. Trials have shown that individuals at high risk of developing type 2 diabetes can significantly reduce their risk with certain interventions, such as lifestyle modification programs [4].

Regular physical activity reduces the risk of diabetes and high glycaemia, and is an important contributor to weight management, another risk factor for diabetes [1].

Type 2 diabetes needs to be managed. Most people will start with lifestyle changes, such as exercise or weight-loss education [1], as the first line of treatment. However, if these changes don’t help you achieve or maintain your blood glucose targets, medications will be used as a second line of treatment [4]

The management of type 2 diabetes can involve several different medications [4]. If blood glucose is very high or causing symptoms, then insulin may be started as the first treatment [4]. Eventually, many people with type 2 diabetes end up taking insulin as their treatment [3].


Gestational diabetes

Gestational diabetes is a temporary condition [1] that starts or is first recognised in pregnancy [6]. It is usually detected and diagnosed through prenatal health screening, rather than reported symptoms [1].People with gestational diabetes have an increased risk of some complications during pregnancy and delivery [1]. These complications can also affect the baby [1].

There are several things that need to be monitored if a person has gestational diabetes [7]. These include:

  • Daily self-monitoring of blood glucose levels
  • Ultrasound scans to assess how the baby is growing 
  • Monitoring of blood pressure and protein in the urine
  • Management for gestational diabetes includes [7]:

Nutritional counselling to ensure that the calories in food are enough to meet the needs of pregnancy while helping to achieve target blood glucose goals

Insulin treatment may be started if nutritional therapy is not sufficient to manage blood glucose

Ensuring that the baby is delivered at the right time, which is usually during the 38th week of being pregnant unless there is a reason for the baby to be born earlier.

Diabetes is a very common condition, shared by millions of people worldwide [1]. There are different types of diabetes [3].

Diabetes complication

Diabetes can cause a range of complications [1], but it is important to know that there are a number of actions you can take to reduce your risk of complications significantly [3].


Diabetes of all types can lead to complications in many different parts of the body [1].

Acute (short-term) complications can include conditions related to high blood glucose such as diabetic ketoacidosis (DKA) and hyperosmolar coma [1, 4]. Low blood glucose can also occur in all types of diabetes and may result in loss of consciousness or seizures [1].

Long-term complications can be classified as either microvascular or macrovascular [3]. Microvascular complications include nervous system damage (neuropathy), kidney problems and renal system damage (nephropathy) and vision issues (retinopathy) [1, 3]. Macrovascular complications include cardiovascular disease, stroke, and peripheral vascular disease — which may lead to infection and injury that don’t heal, especially in the feet [1, 3].

While a long list of complications can seem scary, there are things that you can do to reduce the risk of these problems occurring. Improving your blood glucose levels, blood pressure and cholesterol levels can all reduce your risk of complications [3]. Good management of your diabetes using medicines, following a healthy lifestyle, self-care, and regular screening can help to prevent complications from diabetes [1].

A landmark trial for people with type 1 diabetes, carried out in the late 1980s and 90s, showed that meticulous glycemic management reduced the risks of eye, kidney and nerve damage by between 30 and 90% [8].


1. Global report on diabetes. 2016. World Health Organisation. Available from Accessed June 2022.

2. International Diabetes Federation, IDF Diabetes Atlas 10th edition, 2021. 

3. Deshpande, AD, et al. Epidemiology of Diabetes and Diabetes-Related Complications. Physical Therapy. 2008; 88(11): 1254–1264,