Contents
Introduction
Diabetes, scientifically known as diabetes mellitus, is a multitype chronic condition involving high blood glucose levels resulting from the body’s inability to produce enough or any insulin, a hormone that acts as a glucose regulator [1] [2]. People have known about diabetes for a very long time. The first case of diabetes is thought to have been recorded as early as 1500 BC, while the first evidence of diabetes was documented in the 2nd century [3]. Over the past decade, the number of cases and the prevalence of diabetes have been steadily increasing [4]. The International Diabetes Federation 2021 report showed that 10.5% of the adult population worldwide has diabetes, with almost half being unaware of their condition [5]. Over time, diabetes can lead to serious health complications such as blindness, kidney failure, and heart attack. In 2019, 1.5 million deaths were attributed to diabetes. An additional 460,000 kidney disease-related deaths were caused by diabetes and around 1 in 5 cardiovascular-related deaths were attributed to high blood glucose [6] making diabetes one of the top 10 leading causes of morbidity and mortality worldwide [7].
November is Diabetes Awareness Month, dedicated to raising awareness, and November 14th is World Diabetes Day. This date was chosen in honor of Dr. Frederick Banting who discovered insulin in 1921 and was born on this day in 1891.
Insulin
Insulin is made by the pancreas and helps your body control your blood sugar levels. When food breaks down into glucose, it enters the bloodstream where insulin helps move the glucose into the cells to become energy [8]. When there is not enough insulin in the body, glucose levels in the blood keep increasing, and cells are starved for energy.
The discovery of insulin by Dr. Banting and medical student Charles Best in 1921 has been considered the most important breakthrough in the path to curing diabetes and it has been characterized as ‘the leading medical miracle of the 20th century’. Up until Banting and Best’s discovery, diabetes was considered a fatal condition, with people dying within days or months of diagnosis. Only a small number of patients would survive for a few years under a very strict diet that would lead to malnourishment [9]. Within a year of the discovery, insulin treatment was made available to many diabetic patients and it remains a key treatment for diabetes until today. 2023 marks 100 years since the 1923 Nobel Prize in Physiology or Medicine was awarded to Dr. Banting for the discovery of insulin.
Symptoms
Symptoms of diabetes vary in severity and may occur suddenly, depending on the specific type of diabetes. Common symptoms include:
- Blurred vision
- Unintentional weight loss
- Constant need to urinate
- Increased thirst
- Fatigue
- Longer time for wounds to heal
Untreated diabetes leads to prolonged high blood glucose levels which could cause atherosclerosis and poor blood supply to tissues and organs that could subsequently result in heart disease, stroke, and wounds that are slow to heal, especially in the lower limbs, making them susceptible to infections which when severe, may require amputation. High blood glucose levels can also cause damage in the blood vessels of the nerves, leading to peripheral neuropathy. Peripheral neuropathy can affect different parts of the body such as the digestive system causing nausea and vomiting or spread to the fingers and toes causing numbness. Another common complication of untreated diabetes is vision loss and blindness in young and middle-aged patients, as well as kidney failure.
Types of diabetes
Type 1 Diabetes
Type 1 diabetes, once called insulin-dependent or juvenile diabetes, is an autoimmune, chronic condition that is often diagnosed in childhood or adolescence, but could also develop in adulthood [10]. When a person has type 1 diabetes, their immune system attacks and inhibits the pancreatic cells responsible for producing insulin. This results in very little to no insulin production [11]. The causes leading to type 1 diabetes are not entirely understood, but it is believed that genetics and environmental factors, such as viruses, might trigger the condition. Nine in 10 people with type 1 diabetes do not have any family members with the same condition, however, over 50 genes are thought to confer increased risk of developing type 1 diabetes [12]. Unlike other diabetes types that are preventable with lifestyle modifications and a specific diet, type 1 diabetes is not preventable.
Symptoms of type 1 diabetes might take years to start appearing, but once they appear they can be severe, even life-threatening [13]. If a doctor suspects type 1 diabetes, they will request blood tests to check the glucose levels in the body. There are various blood tests that can be performed, such as a glycated hemoglobin test that shows the average glucose level over the last 2-3 months, oral glucose tolerance test (OGTT), where blood is drawn at specific time intervals after consuming a high glucose drink to see how the glucose was processed by the body [14], blood tests that show glucose levels at random times, and a fasting blood sugar test that is performed on an empty stomach [9]. If a person is diagnosed with diabetes, testing for antibodies against the pancreatic cells producing insulin is performed to rule out other types of diabetes, as these antibodies are only present in type 1 diabetes.
Although there is no cure for type 1 diabetes, treatment and clinical management should begin immediately following a diagnosis. The most common form of clinical management is insulin injection and blood glucose monitoring [15]. Oral intake of insulin would not be effective as stomach enzymes break down the insulin before it has time to work. Another way to get insulin into the body is through an insulin pump, a small device attached to the body programmed to deliver insulin automatically throughout the day and night [16]. Type 1 diabetics need to be careful to inject insulin at the right dosage to avoid low blood glucose, also known as hypoglycemia, a life-threatening condition that needs to be treated immediately. Other supplementary ways to stay healthy while living with type 1 diabetes are to count carbohydrates, fats, and proteins intake, eat healthily, exercise regularly, and maintain a healthy body weight.
Type 2 Diabetes
Type 2 diabetes, previously known as non-insulin dependent or adult-onset diabetes, is a chronic progressive condition resulting from high blood glucose levels in the body. Risk factors include being overweight, having a family history of type 2 diabetes, and not being physically active. More than 95% of people with diabetes have type 2 diabetes [4].
Contrary to type 1 diabetes, the pancreas of people with type 2 diabetes produces small amounts of insulin, but not enough to regulate glucose. Due to the progressive state of type 2 diabetes, it is divided into different stages [17]. The first stage, occurring years before type 2 diabetes manifestation, is the insulin resistance stage, which is the first sign of blood glucose issues. During this stage, insulin cannot regulate glucose correctly and that causes the pancreas to produce more to keep the blood glucose levels normal. While insulin resistance is difficult to diagnose, some signs include obesity and high glucose levels while fasting. Over time, it becomes more difficult for the pancreas to keep up with the increasing production of insulin, resulting in the second stage of type 2 diabetes, called the prediabetes stage. In this stage, blood glucose is higher than healthy levels but not high enough to be considered diabetes. Patients with insulin resistance and prediabetes could prevent developing type 2 diabetes by maintaining a healthy weight, exercising, and eating a healthy diet. The third stage is when it manifests into type 2 diabetes and the fourth stage is when diabetes starts causing vascular complications such as retinopathy and atherosclerosis.
Symptoms of type 2 diabetes are frequently mild and can go unnoticed. The most common symptoms are increased thirst, fatigue and a constant urge to go to the toilet [18]. Blood tests for type 2 diabetes are the same as for type 1 diabetes [19].
Once it manifests there is no cure for type 2 diabetes but managing the condition and preventing any potential complications such as vision loss or kidney failure is easier than for type 1 diabetes. Certain medication such as insulin, or metformin, may be prescribed to patients to help them reduce their glucose levels. Lifelong management of type 2 diabetes includes blood glucose monitoring, healthy eating, regular exercising and maintaining a healthy weight [20]. In fact, some people with type 2 diabetes manage to put their condition into remission provided they maintain their healthy lifestyle and diet. Obesity is a major risk factor for diabetes type 2 development, and accounts for approximately 52% of type 2 diabetes-associated disability and life-threatening complications [7]. Raising awareness for type 2 diabetes and its associated risk factors, most of which can be manageable through proper diet and exercise, can encourage people to live a healthier lifestyle and reduce their risk of developing this ancient condition which is more relevant than ever today.
Gestational Diabetes
Gestational diabetes is a condition some expectant mothers develop during pregnancy, when the pancreas cannot meet the increasing needs of insulin production and the levels of blood glucose become high [21]. Gestational diabetes can develop at any stage of pregnancy, but mostly it is observed in pregnant women during their second or third trimester, and usually resolves after giving birth.
Pregnant women with this condition, as well as women with type 1 or type 2 diabetes, have an increased risk for high blood pressure and pregnancy complications such as preeclampsia, a life-threatening condition for both the mother and the baby, and are more likely to need a cesarean delivery [22]. Women with gestational diabetes are also more likely to develop type 2 diabetes in the future. The baby has also an increased risk for complications, such as being born overweight which could complicate delivery, preterm delivery with respiratory difficulties, low blood sugar that might result in seizures, and a higher risk of developing type 2 diabetes later in life. If left untreated, gestational diabetes may also result in stillbirth.
Even though any woman is at risk for developing gestational diabetes, the risk increases if the mother [22]:
- Is over 25 years old
- Is overweight
- Had developed gestational diabetes in a previous pregnancy
- Had previously delivered an overweight baby
- Has family history of diabetes
Screening for gestational diabetes is usually performed between the 24th and 28th week of pregnancy with an oral glucose tolerance test (OGTT). Guidelines vary around the world, with some countries making screening for gestational diabetes part of standard procedure whereas others only screening women who fall under the risk category [23].
Gestational diabetes is a manageable condition, especially when identified early in pregnancy. As in type 2 diabetes, a pregnant woman can improve her condition by making lifestyle changes such as being more active, having a healthier diet and monitoring her blood glucose levels to ensure they stay within a healthy range. If lifestyle changes do not decrease blood glucose levels, medication such as injectable or oral insulin can be prescribed. Close monitoring of mother and baby should continue after delivery, to ensure that blood glucose levels return within the healthy range. Doctors also suggest performing a diabetes risk assessment test, due to increased risk for type 2 diabetes or prediabetes, every few years.
Other types of diabetes
As well as the three main types of diabetes, there are other types of diabetes that are not that common [24].
Maturity-onset diabetes of the young (MODY) is a rare monogenic form of diabetes which is caused by a mutation on a single gene. This type of diabetes is hereditary and if a parent has the mutation, there is a 50% chance of a child inheriting it as well and developing MODY by the age of 25. Due to MODY being rare, it is often mistaken for and treated as type 2 diabetes. However, depending on the specific mutation treatment might differ, and insulin intake might not be necessary. Genetic testing for the rest of the family should be considered when someone is diagnosed with MODY, to identify members with the same mutation and learn the risk of having a child with the same condition.
Neonatal diabetes is another rare monogenic form of diabetes that is identified in infants under the age of 6 months. It is caused by a mutation in a gene responsible for insulin production. Other than increased levels of blood glucose in the body, infants with neonatal diabetes also present with developmental delay and even epilepsy. Infants with mutations in specific genes, such as KCNJ11 and BCC8, do not need insulin and instead should be taking a higher than usual dosage of an oral hypoglycemic drug that stimulates the pancreas into secreting insulin. This emphasizes the role of genetic testing in guiding optimal treatment in infants diagnosed with neonatal diabetes.
Cystic fibrosis-related diabetes (CFRD) is a type of diabetes common in people with cystic fibrosis (CF) which results from pancreatic scarring from CF-related inflammation. Diagnosis is achieved through glucose monitoring or with an oral glucose tolerance test. Treatment of CFRD is similar to type 1 and type 2 diabetes and includes lifestyle modifications and insulin injections.
Steroid-induced diabetes is a type of diabetes that develops in people who take steroids, especially those who are already at a higher risk for developing type 2 diabetes. Steroids can increase the blood glucose either by causing the liver to produce more glucose, stopping the muscles and fat cells from absorbing glucose, or reducing the body’s sensitivity to insulin. These effects can become permanent even after a person stops taking steroids, and they end up struggling with steroid-induced diabetes throughout their lives.
Alström syndrome and Wolfram syndrome are two rare genetic conditions with common features that include increased blood glucose, diabetes, and diabetes-related complications.
Latent autoimmune diabetes in adults (LADA) is a type of diabetes that is similar to both type 1 and type 2 diabetes, which is why some people call it type 1.5 diabetes. Symptoms are the same as common types of diabetes, and although they do not appear as fast as type 1, they appear faster than type 2. People with LADA are often misdiagnosed with type 2 diabetes but if tested for antibodies, like people with type 1 diabetes, they will have them. Treatment is case-specific.
Type 3c diabetes is a type of diabetes that develops when another disease not related to diabetes, such as pancreatitis or pancreatic cancer, causes damage or scarring to the pancreas. This specific type of diabetes is not that well-known and people suffering from it are often misdiagnosed with type 2 diabetes.
Conclusion
Diabetes is a multitype condition resulting from insufficient insulin to regulate blood glucose in the body. Currently, diabetes affects 1 in 10 people worldwide but despite its high prevalence there is still a lot to be discovered and understood. Since the discovery of insulin 100 years ago, there have not been any major breakthroughs in the understanding and treatment of diabetes, yet the number of people being diagnosed annually is constantly increasing. Diabetes is still a major cause of global morbidity and mortality, causing an increased burden for diabetics and healthcare institutions around the world. As a result, the next big breakthrough is needed, whether this lies in the causes of diabetes, treatment, or cure.
References
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