Type 2 diabetes: definition
What is type 2 diabetes?
Type 2 diabetes (T2D), formerly called "non-insulin-dependent diabetes" or "adult-onset diabetes", is a chronic disease characterised by a continuous excessive level of glucose in the bloodstream (hyperglycemia).
Type 2 diabetes is a chronic disease characterised by a continuous excess of glucose in the blood (hyperglycemia).
It usually appears in adults over 40 years old but its diagnosis may be late, due to the initial progression of the disease.
Patients with T2D are at risk of numerous complications, in particular cardiovascular, renal, ophthalmic, etc.
Glucose (sugar) is the fuel for the body's cells: they need it all the time to function properly (especially the brain). The glucose that circulates in the bloodstream comes from food (cereal, dairy products, fruit, etc.) or from our energy reserves (produced by the liver or the muscles).
In healthy subjects, the pancreas secretes hormones in order to regulate the level of glucose in the bloodstream (also called glycaemia). The two main hormones secreted by the pancreas are insulin and glucagon. They have opposed roles: insulin allows glucose to enter muscle cells, adipose tissue and liver, where it can be transformed (into glycogen) and stored. Thus the level of glucose decreases.
Glucagon allows the release of glucose stored in the liver, outside of meals, when blood sugar levels are falling: it increases the level of glucose in the bloodstream.
The balance of these hormones keeps blood sugar levels stabilised.
In type 2 diabetes, this regulatory system is altered. There is insulin resistance in muscle cells and the liver, linked to excess visceral fat mass and sedentary lifestyle. At first, the pancreas is able to cope with the situation by increasing its secretion of insulin. But the disease of the beta cells of the pancreas (cell death or apoptosis) gradually decreases the secretion of insulin which is no longer able to compensate for insulin resistance.
At the same time, there is an excess of glucagon, produced by the pancreas, which increases blood sugar levels. To rebalance excessively high sugar levels in the blood, insulin must be produced in large quantities. Over time, the excessive production of insulin will no longer be sufficient to compensate for hyperglycaemia: the pancreas becomes exhausted and insulin secretion decreases (insulinopenia). Type 2 diabetes can develop in this hormonal context.
In comparison, type I diabetes, which most often develops in childhood, results from the destruction of the pancreas cells by the patient’s immune system (it is therefore an autoimmune disease). This provokes insufficient insulin production and the patient requires daily injections of insulin (insulin therapy) throughout their whole life.
A rapidly expanding disease
Type 2 diabetes is considered to be a real epidemic. According to WHO, the number of type 2 diabetics in the world rose from 108 to 422 million between 1980 and 2014. This increase is mainly due to the aging of the population, but also to sedentary lifestyle and unhealthy diet which both lead to excessive weight.
There are currently 4.7 million people living with diabetes (both types) in the UK. 90% of them have type 2 diabetes.
Symptoms and diagnosis of type 2 diabetes
Hyperglycaemia caused by type 2 diabetes remains asymptomatic for a long time (that means without symptoms), and the disease develops silently for several years. It is usually discovered accidentally, during a routine blood test or when certain complications arise.
Thus, the diagnosis of type 2 diabetes is often delayed, when patients are around 60-65 years old, and is established via a blood glucose test on an empty stomach. Diabetes is confirmed when fasting blood sugar level is 1.26 g / L or more (after two measurements) or 2 g / L or more at any time of the day.
Here is what @Paracelsus, a member of Carenity Spain, tells us about his diagnosis, his state of health today and how he has managed to control his blood sugar.
“I found out that I had diabetes in 2008, at the age of 48, when I had probably had glucose levels above recommended levels for years (at least 8 years). It was only during a medical examination to pass my airplane pilot's license that I became acquainted with diabetes, this silent enemy ... ”
Unlike type 1 diabetes, the onset of which is sudden, type 2 diabetes is preceded by an intermediate phase called prediabetes. It is described by the WHO (World Health Organisation) using 2 criteria: a fasting (8 hours) blood sugar level between 1.1 and 1.25 g / L , which is measured twice (knowing that a normal fasting blood sugar level is between 0.7 and 1.1g / L), is linked to glucose intolerance of all the body’s cells (in particular the liver and muscles), causing the significant increase in blood glucose after absorption of sugar. This phase is reversible, especially by sticking to a healthy diet and a healthy lifestyle in general, and it is possible to limit the progression of the disease to type 2 diabetes and thus reduce the risk of cardiovascular complications.
When type 2 diabetes develops, the patient may experience severe thirst, increased appetite, frequent urination, or chronic fatigue. Weight loss and blurred vision may also be observed. Finally, there is an increased susceptibility to infections (boils, genital candidiasis, genital pruritus).
In addition, other tests, such as post-prandial blood sugar level (measurement of blood sugar after a meal), induced blood sugar (measurement of the rate of changes in blood sugar after ingesting glucose) or the level of glycated haemoglobin (haemoglobin on which the glucose is fixed, its level must be less than 7% of the total haemoglobin, but the value can be adjusted by the doctor according to the patient’s profile), can also confirm or clarify the diagnosis.
If you are living in England, and you are between 40 and 74 years old, you can get a free NHS Health Check, to find out if you are at risk for developing type 2 diabetes, or other chronic conditions. It can also help you spot the first signs of these conditions and get advice on what to do next.
Complications of type 2 diabetes
When type 2 diabetes is poorly controlled and hyperglycaemia persists over time, it can cause various complications, especially those of the vascular system (of both small (microvascular) and large vessels (macrovascular)).
The most common complications are:
- cardiovascular: cholesterol deposits on the walls of the blood vessels with the formation of atheromatous plaques, which lead to partial or total obstruction of the vessels. This carries a risk of myocardial infarction (multiplied by 3 to 5% in type 2 diabetics), high blood pressure, stroke and poor circulation in the arteries of the legs (arteritis of the lower limbs).
- kidney: diabetic nephropathy and damage to the lining of the kidneys which allows proteins (especially albumin) to pass into the urine. Without treatment, it progresses to chronic renal failure (every year, 3,000 diabetics start kidney dialysis or have a kidney transplant).
- neurological: hyperglycaemia alters the structure of peripheral nerves (which control muscles and skin sensitivity) and nerves of the autonomic nervous system (which control various organs). This is called diabetic neuropathy.
- ophthalmic: capillary micro-occlusions (the smallest vessels) degrade the retina, which can lead to blindness.
- Foot damage: insensitivity to pain exposes the diabetic patient to foot wounds that are difficult to heal and promote infection, which can lead to amputations.
- sensitivity to infections: skin (abscess and gangrene), oral (gingivitis and periodontitis) and genital (urinary tract infections and vaginal yeast infection)
- liver disease: non-alcoholic steatosis or "fatty liver disease" (NAFLD / NASH)
- erectile dysfunction: related to vascular involvement and diabetic neuropathy.
Diabetic ketoacidosis (which is a life-threatening emergency) can occur in patients suffering from T2D when there is a significant increase in the body's need for insulin (myocardial infarction, severe infection, major surgery, etc.). The sugar no longer enters the cells due to lack of insulin, and the body therefore uses fatty acids for energy, which results in the production of ketone bodies. Clinical signs include nausea, abdominal pain and weight loss, followed by rapid breathing, acetone odour in the breath, general dehydration and disturbances of consciousness. Ketoacidosis must be treated urgently because it can progress to coma and even cause the patient’s death.
Hyperosmolar coma (also referred to as hyperosmolar hyperglycemic syndrome (HHS)) affects elderly patients with T2D. It is caused by severe dehydration due to severe hyperglycaemia. Its triggers are infections, diarrhea or diuretics. This complication begins gradually: the feeling of intense thirst and severe muscle fatigue should alert you. It is also an emergency, as it can lead to death.
Finally, hypoglycaemia occurs when the dose of treatment (insulin and / or sulfonylureas) is too high, in the event of unusual physical activity or after a meal that is too poor in carbohydrates. To avoid this situation, it is necessary to be able to recognize the symptoms: sweating, tremors, pallor, blurred vision, food cravings, weakness and mood swings. When these symptoms appear, stop exercising and take 3 lumps of sugar, a small box of juice or 2 teaspoons of honey or jam.
Causes and risk factors of type 2 diabetes
There isn’t a single cause, but several risk factors for type 2 diabetes:
- genetic factors: family history with a first-degree relative (mother, father, brother, sister) suffering from type 2 diabetes, but there are also certain populations that are more particularly affected by the disease (especially people of African, Latin American or Asian origin)
- environmental factors: unbalanced diet (too many calories) and sedentary lifestyle that promote obesity. Smoking and high blood pressure are also implicated in type 2 diabetes.
- gut microbiota which depends on genetic predisposition and is very sensitive to the lifestyle (nutrition, drugs, sedentary lifestyle) of its host could constitute in itself a risk factor (the microbiota signature of a diabetic patient). A healthy lifestyle could therefore prevent the development of type 2 diabetes.
- for women, pregnancy is a risk factor: following the onset of gestational diabetes or the birth of a child weighing more than 4 kg.
Treatments for type 2 diabetes
Lifestyle and diet
A balanced diet (and weight loss if necessary) is the basic treatment for type 2 diabetes and can slow its progression.
- The size of the portions of the following 3 food groups that are natural sources of carbohydrates should be controlled: fruit (fructose, glucose), dairy products (lactose) and starches (starch).
- It is recommended to eat 3 main meals a day, which are balanced in carbohydrates, as well as in fats and proteins, and to control the size of the portions.
- Patients should prefer foods with a low glycemic index (the rate at which food can increase an individual's blood sugar level).
- Limit simple fatty acids of animal or vegetable origin, avoid trans fatty acids as much as possible (industrial foods produced from oil processing), favour monounsaturated fatty acids (omega 9 including oleic acid from oil olive) and polyunsaturated (especially omega 3, which can be found for example in fatty fish such as mackerel, sardines, salmon, etc.)
- Diversify the sources of protein: animal (rich in amino acids, iron) and vegetable (starch, micronutrients), limit fatty meats, consume 3 dairy products per day, and regularly include legumes and cereal in your diet.
- Increase your fiber intake (especially soluble fiber, contained in oat bran, legumes or citrus fruits)
- Snacks should only be taken in case of necessity (hypoglycaemia) or special events (physical activity, stress, etc.) and it should be simple foods (unrefined) such as fruit, milk, yogurt or bread.
- Foods and drinks rich in added sugar (sodas) should be avoided, or even eliminated from your diet altogether.
- Alcohol should be consumed moderately if diabetes is well-managed (and alongside carbohydrate intake), otherwise it should be avoided.
- Stopping smoking improves the effectiveness of insulin and therefore lowers blood sugar levels.
In addition, it is essential to combine a healthy diet with regular physical activity. By physical activity we mean any type of exercise that causes muscles to contract and thus increases energy expenditure. It improves muscle capacity and endurance, helps reduce the risk of cardiovascular disease and control cholesterol and weight, promotes good-quality sleep and reduces stress. Finally, exercise increases the consumption of glucose and thus allows better control of blood sugar levels and diabetes in general.
As for the diet, the recommendations are the same for the general population and for people with diabetes: the WHO recommends 150 minutes (or 2h30) per week of endurance sport of moderate intensity (such as brisk walking, cycling, swimming…), on average that means 30 minutes a day. It is best to start with a low-intensity activity (slow walking, cleaning, gardening, etc.), and then gradually increase, if possible, its intensity and duration.
“Follow the doctor's recommendations, avoid hypoglycaemia, avoid stress, walk, swim, exercise gently, have a balanced diet, a healthy lifestyle, a good sleep, keep a self-monitoring journal, practice relaxation techniques, always have 3 lumps of sugar on you in case of hypoglycaemia, be aware of the signs of complications in order to react quickly, live as serenely as possible, do what you enjoy and go out.
Let's take control of our disease in order to better manage it! ”
As a second-line treatment, oral antidiabetics (tablets) and / or injections (insulin or GLP-1 analogue) are prescribed.
There are different types of treatments with different mechanisms of action:
- Biguanides including metformin (Glucophage®), a first-line treatment: it causes a decrease in glucose production, improves the sensitivity of the liver and muscles to insulin and reduces intestinal glucose absorption. This drug allows blood sugar values to return to normal without the risk of hypoglycaemia. On the other hand, metformin can cause digestive disorders (bloating, diarrhea): it is possible to reduce these effects by modifying, with the approval of the doctor, the drug, its dose or method of administration (for example take it at the end of a meal).
- Sulphonylureas (Diamicron®, Glibenclamid®, Glimiperid®), and glinides (Repaglinid®, Starlix®): they stimulate insulin secretion by the pancreas to the extent of its capacity, and can therefore cause hypoglycaemia (you should be vigilant!).
- Alpha-glucosidase inhibitors (Acarbose®): delay the absorption of carbohydrates after meals (there is no risk of hypoglycaemia).
- Incretins: substances secreted by the body at the start of a meal to increase insulin secretion. They can be injected directly (analogues of GLP-1, such as Byetta ®, Victoza ®, Bydureon ®, Trulicity ®, Ozempic ®), and it is also possible to decrease their degradation by the body using gliptins (also called DPP-4 inhibitors, such as Januvia® , Galvus®, Onglyza®). They stimulate insulin secretion only when blood sugar is high and thus reduce the risk of developing hypoglycaemia. They also reduce glucagon secretion (and thus the production of glucose by the liver). Finally, they slow down gastric emptying and thus increase the feeling of fullness.
- SGLT-2 inhibitors, new oral hypoglycaemic agents that are being developed: increase the elimination of glucose into the urine and thus decrease the level of glucose in the bloodstream.
Finally, in the event of insulinopenia (deficit in insulin secretion), the injection of insulin becomes necessary. It is recommended for patients who have not achieved glycemic control (HbA1c ≥ 8%) despite appropriate oral antidiabetic treatment (OAD) and healthy lifestyle. According to the CNAMTS study, 76.1% of type 2 diabetics treated are on OAD alone, 10.4% are on insulin combined with OAD and 13.5% on insulin alone.
Thus, depending on the patient's glycaemic profile, an injection plan is established by the doctor:
- slow insulin: if blood sugar level is high in the morning and drops during the day
- rapid insulin: if blood sugar level rises after meals
- a combination of the two types of injectable insulin: if the patient experiences blood sugar spikes at different times of the day.
Insulin injections can cause hypoglycaemia.
Living with type 2 diabetes
A progressing disease
Type II diabetes is related to insulin resistance, which can be provoked by excessive weight. It is therefore necessary to exercise regularly, and to control the daily intake of carbohydrates and lipids. Insulin-sensitising drugs (such as metformin) can be added to treatment regimen when a healthy lifestyle is no longer sufficient to control diabetes.
If treatment becomes insufficient and diabetes is poorly controlled, insulin-secreting drugs can be prescribed (such as sulfonylureas or glinides).
Over time, the cells of the pancreas become depleted and insulin secretion decreases: diabetes then becomes insulin-dependent and treatment with injectable insulin becomes necessary.
In type 2 diabetes, glycaemic self-monitoring, which the patient can carry out using a blood glucose meter (Accu-Chek®, OneTouch®, FreeStyle®, etc.) is not recommended at the onset of the disease (unlike type 1 diabetes), but becomes necessary when insulin therapy is used (treatment with injectable insulin).
However, self-monitoring of blood glucose can be temporarily helpful, when the patient begins to follow a balanced diet and takes up exercise, or during change of treatment (for sulfonylureas, for example).
Fasting blood sugar monitoring by healthcare professionals is needed once or twice a year.
Measuring glycated haemoglobin (HbA1c) is essential for diabetes monitoring. It reflects the average blood glucose values over the past 2 months and must be less than 7% of total haemoglobin (but this percentage is adjusted by the doctor depending on the patient). If this goal is reached and the treatment is not changed, the blood test should be carried out every 6 months. On the other hand, if diabetes control is insufficient or there is a change of treatment, the patient should be tested every 3 months.
As for cardiovascular risk factors, a lipid panel and testing for good (HDL) and bad (LDL) cholesterol should be carried out once a year.
Renal function should also be monitored annually: serum creatinine levels, creatinine clearance (glomerular filtration rate) and microalbuminuria are essential because they can show renal damage. Microalbuminuria, in particular, is a marker for cardiovascular disease in type 2 diabetes.
Finally, screening for other complications is necessary: annual cardiovascular examination (blood pressure control, pulse control in peripheral arteries, search for cardiac and arterial murmurs, electrocardiogram at rest, etc.), annual ophthalmological assessment to prevent retinopathy, annual examinations for neurological complications (peripheral neuropathy), as well as annual examination of the feet (small lesions, trophic disorders, cracks, etc.).
Type 2 diabetes cannot be cured, for now. But we know how to prevent its development and its complications. It is more or less all about a healthy lifestyle, which includes a healthy and balanced diet, and regular exercise.
Published 13 Nov 2017 • Updated 29 Dec 2021