diabetes, blood, finger



Diabetes is a chronic disease, which occurs when the pancreas does not produce enough insulin, or when the body cannot effectively use the insulin it produces. This leads to an increased concentration of glucose in the blood (hyperglycaemia).

Blood glucose chart


The expected values for normal fasting blood glucose concentration are between 70 mg/dL (3.9 mmol/L) and 100 mg/dL (5.6 mmol/L). When fasting blood glucose is between 100 to 125 mg/dL (5.6 to 6.9 mmol/L) changes in lifestyle and monitoring glycemia are recommended. If fasting blood glucose is 126 mg/dL (7 mmol/L) or higher on two separate tests, diabetes is diagnosed. An individual with low fasting blood glucose concentration (hypoglycemia) – below 70 mg/dL (3.9 mmol/L) – will experience dizziness, sweating, palpitations, blurred vision and other symptoms that have to be monitored. Increased fasting blood glucose concentration (hyperglycemia) is an indicator of a higher risk to diabetes. An individual’s fasting blood plasma glucose (FPG) may be in the normal range because the individual is not diabetic or because of effective treatment with glucose-lowering medication in diabetics. Mean FPG at the national level is used as a proxy for both promotion of healthy diets and behaviours and, treatment of diabetes.

Diabetes and its effects on health

Post prandial

Test results vary by age and are usually measured in milligrams per deciliter (mg/dL). Normal results for the 2-hour postprandial test based on age are: 

  • For those who don’t have diabetes: less than 140 mg/dL 
  • For those who have diabetes: less than 180 mg/dL  

If your blood glucose level is still high 2 hours after you’ve eaten, or if it is high 1 hour after a gestational diabetes glucose tolerance test, it could mean you have diabetes.

Diabetes blood sugar chart


If you had a random blood glucose test, a normal result depends on when you last ate. Most of the time, the blood glucose level will be 125 mg/dL (6.9 mmol/L) or lower.

A level of 200 mg/dL (11 mmol/L) or higher often means you have diabetes.

Diabetes and its effects on health

Type of diabetes

There are several kind of diabetes based on there action with insulin and genetics make up.

Type 1 diabetes

Type 1 diabetes (previously known as insulin-dependent, juvenile or childhood-onset) is characterized by deficient insulin production and requires daily administration of insulin. In 2017 there were 9 million people with type 1 diabetes; the majority of them live in high-income countries. Neither its cause nor the means to prevent it are known.

Type 2 diabetes

Type 2 diabetes affects how your body uses sugar (glucose) for energy. It stops the body from using insulin properly, which can lead to high levels of blood sugar if not treated. 

Over time, type 2 diabetes can cause serious damage to the body, especially nerves and blood vessels.

Type 2 diabetes is often preventable. Factors that contribute to developing type 2 diabetes include being overweight, not getting enough exercise, and genetics. 

Early diagnosis is important to prevent the worst effects of type 2 diabetes. The best way to detect diabetes early is to get regular check-ups and blood tests with a healthcare provider. 

Symptoms of type 2 diabetes can be mild. They may take several years to be noticed.  Symptoms may be similar to those of type 1 diabetes but are often less marked. As a result, the disease may be diagnosed several years after onset, after complications have already arisen.

More than 95% of people with diabetes have type 2 diabetes. Type 2 diabetes was formerly called non-insulin dependent, or adult onset. Until recently, this type of diabetes was seen only in adults but it is now also occurring increasingly frequently in children.

Gestational diabetes

Gestational diabetes is hyperglycaemia with blood glucose values above normal but below those diagnostic of diabetes. Gestational diabetes occurs during pregnancy.

Women with gestational diabetes are at an increased risk of complications during pregnancy and at delivery. These women and possibly their children are also at increased risk of type 2 diabetes in the future.

Gestational diabetes is diagnosed through prenatal screening, rather than through reported symptoms.

Impaired glucose tolerance and impaired fasting glycaemia

Impaired glucose tolerance (IGT) and impaired fasting glycaemia (IFG) are intermediate conditions in the transition between normality and diabetes. People with IGT or IFG are at high risk of progressing to type 2 diabetes, although this is not inevitable.


prediabetes, blood sugar levels are higher than normal, but not high enough for a type 2 diabetes diagnosis. Prediabetes raises your risk for type 2 diabetes, heart disease, and stroke. But there’s good news. If you have prediabetes, a CDC-recognized life style change programme can help you take healthy steps to reverse it.

Monogenic diabetes 

Monogenic diabetes is a rare condition, different from both type 1 and type 2 diabetes. It’s caused by a mutation in a single gene. If a parent has this mutation, their children have a 50p per cent chance of inheriting it.Since monogenic diabetes is so rare, people can often get misdiagnosed.

And in some cases of monogenic diabetes, the condition can be managed with specific tablets and doesn’t require insulin treatment. That’s why it’s incredibly important to understand rare forms of diabetes and diagnose them correctly.

There are two types of monogenic diabetes – Neonetal and MODY.

Maturity onset diabetes of the young (MODY)

MODY is caused by a mutation (or change) in a single gene. If a parent has this gene mutation, any child they have, has a 50% chance of inheriting it from them. If a child does inherit the mutation they will generally go on to develop MODY before they’re 25, whatever their weight, lifestyle, ethnic group etc.

Most common types of MODY

Neonatal diabetes

  • Neonatal diabetes is caused by a change in a gene which affects insulin production. This means that levels of blood glucose (sugar) in the body rise very high.
  • The main feature of neonatal diabetes is being diagnosed with diabetes under the age of 6 months.
  • As well as this, about 20% of people with neonatal diabetes also have some developmental delay (eg muscle weakness, learning difficulties) and epilepsy.
  • Neonatal diabetes is very rare, currently there are less than 100 people diagnosed with it in the UK.
  • There are two types of neonatal diabetes – transient and permanent. As the name suggests, transient neonatal diabetes doesn’t last forever and usually resolves before the age of 12 months. But it usually recurs later on in life, generally during the teenage years. It accounts for 50–60% of all cases. Permanent neonatal diabetes as you might expect, lasts forever and accounts for 40–50% of all cases.

Wolfram Syndrome

Wolfram Syndrome is a rare genetic disorder which is also known as DIDMOAD syndrome after its four most common features (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness).

  • Diabetics Millitus: This is a different type of diabetes than the more common type 1 as it’s not an autoimmune condition (where the body has destroyed the insulin producing cells). You also don’t tend to get microvascular complications like retinopathy (which can cause blindness) or nephropathy (which can cause kidney failure). But it’s treated in the same way as type 1 diabetes with insulin injections, blood testing, following a healthy balanced diet and getting regular physical activity. Everyone with Wolfram Syndrome is likely to have diabetes at some point.
  • Diabetes insipidus: This is where the body can’t concentrate urine because the posterior pituitary gland (found at the base of the brain) isn’t making enough of the hormone vasopressin. This means that you get very thirsty and need to pass urine frequently, and your urine is very dilute. About half of people with Wolfram Syndrome have diabetes insipidus.
  • Optic atrophy: This means that the optic nerve has wasted away and causes colour blindness and gradual loss of vision. Everyone with Wolfram Syndrome will have optic atrophy at some stage.
  • Deafness: It can be difficult to hear high pitched sounds or to hear in a crowded room. About two thirds of people with Wolfram Syndrome will have hearing loss and about one in four of these will need a hearing aid.
  • Renal problems: This can cause bedwetting, needing to pass urine frequently and loss of bladder control. Even when the symptoms of either type of diabetes are controlled, you can still get these symptoms, as they are caused by a problem with the renal tract. About two thirds of people with Wolfram Syndrome have renal problems.
  • Neurological problems: These can include loss of balance, sudden muscle jerks, loss of taste and smell, breathing problems and depression. About a quarter of people with Wolfram Syndrome may have a mental health problem at some stage.
  • Chronic fatigue: People with Wolfram Syndrome have a progressively declining levels of physical stamina. As this condition progresses they will need increasingly greater amounts of sleep.

Alström Syndrome

Alström Syndrome is a rare, genetically inherited syndrome which has a number of common features.

  • Retinal degeneration: This is often the first feature of Alström Syndrome that is noticed. Children have nystagmus (wobbly eyes) and photophobia (extreme sensitivity to light). Poor vision can be present even in small babies, and gradual vision loss can lead to blindness.
  • Hearing loss: This is usually noticed before the age of 10. The severity of hearing loss in Alström Syndrome varies considerably.
  • Cardiomyopathy: This means that the heart doesn’t pump as well as it should. It can improve, although not completely, and it can recur in later life.
  • Obesity: Children and young people with Alström Syndrome have a lower energy requirement and generally are less active compared with their peer group; as a result they have a higher risk of obesity. This weight gain tends to be less severe in later life Type 2 diabetes.
  • Type 2 diabetes: In young adulthood, children with Alström Syndrome tend to become resistant to insulin, and can go on to develop Type 2 diabetes. High blood fat levels are also common in people with insulin resistance.
  • Renal (kidney) failure: This might be acute (happening quickly) or chronic (happening over a long period of time). There are a number of reasons why the kidneys fail; one of these is diabetes.
  • Orthopaedic and rheumatology problems: People with Alström Syndrome can have problems with their bones and joints. These include curvature of the spine, spondylitis (excessive thickening of the spine), arthritis and short stature. Other problems such as hypogonadism (defects of the reproductive system), undescended testes, low testosterone, polycystic ovaries, underactive thyroid and acanthosis nigricans (dark patches of skin) may also be present.

latent autoimmune diabetes in adults (lada)

It’s a type of diabetes which seems to straddle type 1 and type 2 diabetes . Bits of it are more like type 1, and other bits are more like type 2. That’s why some people call it type 1.5 diabetes or type 1 ½ diabetes.

It’s not actually classified as a separate type of diabetes at the moment, but there’s some medical research going on to try and pinpoint exactly what makes it different from type 1 and type 2 diabetes.

Type 3c diabetes

Type 3c diabetes develops because of the damage to the pancreas, which can happen for a few different reasons. And although it’s different to other types, you can get a wrong diagnosis of type 2 because type 3c isn’t well known. Type 3c is not a recognised medical condition. 

steroid-induced diabetes

Steroids can cause high blood glucose (sugar) levels. That’s why some people who take steroids go on to develop diabetes. This is known as steroid-induced diabetes, and is more common in people who are at higher risk of type 2 diabetes.

Cystic fibrosis diabetes

Cystic fibrosis diabetes is a type of diabetes most common in people with cystic fibrosis.

Although people with cystic fibrosis can develop type 1 or type 2 diabetes, cystic fibrosis diabetes is a different condition. It is the most common type of diabetes in people with cystic fibrosis. It has features of both type 1 and type 2, but there are differences in how it develops and is treated.

The build-up of sticky mucus caused by cystic fibrosis can lead to inflammation and scarring of the pancreas. This can damage the cells that produce insulin and lead to high blood glucose (sugar) levels. 

As the pancreas can’t produce enough insulin, blood sugar levels may continue to rise. This is known as cystic fibrosis diabetes.

Symptoms of diabetes

If you have any of the following diabetes symptoms, see your doctor about getting your blood sugar tested:

  • Urinate (pee) a lot, often at night
  • Are very thirsty
  • Lose weight without trying
  • Are very hungry
  • Have blurry vision
  • Have numb or tingling hands or feet
  • Feel very tired
  • Have very dry skin
  • Have sores that heal slowly
  • Have more infections than usual

Complications due to diabetes

Long-term complications of diabetes develop gradually. The longer you have diabetes — and the less controlled your blood sugar — the higher the risk of complications. Eventually, diabetes complications may be disabling or even life-threatening. In fact, prediabetes can lead to type 2 diabetes. Possible complications include:

  • Heart and blood vessel (cardiovascular) disease. Diabetes majorly increases the risk of many heart problems. These can include coronary artery disease with chest pain (angina), heart attack, stroke and narrowing of arteries (atherosclerosis). If you have diabetes, you’re more likely to have heart disease or stroke.
  • Nerve damage from diabetes (diabetic neuropathy). Too much sugar can injure the walls of the tiny blood vessels (capillaries) that nourish the nerves, especially in the legs. This can cause tingling, numbness, burning or pain that usually begins at the tips of the toes or fingers and gradually spreads upward.Damage to the nerves related to digestion can cause problems with nausea, vomiting, diarrhea or constipation. For men, it may lead to erectile dysfunction.
  • Kidney damage from diabetes (diabetic nephropathy). The kidneys hold millions of tiny blood vessel clusters (glomeruli) that filter waste from the blood. Diabetes can damage this delicate filtering system.
  • Eye damage from diabetes (diabetic retinopathy). Diabetes can damage the blood vessels of the eye. This could lead to blindness.
  • Foot damage. Nerve damage in the feet or poor blood flow to the feet increases the risk of many foot complications.
  • Skin and mouth conditions. Diabetes may leave you more prone to skin problems, including bacterial and fungal infections.
  • Hearing impairment. Hearing problems are more common in people with diabetes.
  • Alzheimer’s disease. Type 2 diabetes may increase the risk of dementia, such as Alzheimer’s disease.
  • Depression related to diabetes. Depression symptoms are common in people with type 1 and type 2 diabetes.

Complications of gestational diabetes

Most women who have gestational diabetes deliver healthy babies. However, untreated or uncontrolled blood sugar levels can cause problems for you and your baby.

Complications in baby

  • Excess growth. Extra glucose can cross the placenta. Extra glucose triggers the baby’s pancreas to make extra insulin. This can cause your baby to grow too large. It can lead to a difficult birth and sometimes the need for a C-section.
  • Low blood sugar. Sometimes babies of mothers with gestational diabetes develop low blood sugar (hypoglycemia) shortly after birth. This is because their own insulin production is high.
  • Type 2 diabetes later in life. Babies of mothers who have gestational diabetes have a higher risk of developing obesity and type 2 diabetes later in life.
  • Death. Untreated gestational diabetes can lead to a baby’s death either before or shortly after birth.

Complications in mother

  • Preeclampsia. Symptoms of this condition include high blood pressure, too much protein in the urine, and swelling in the legs and feet.
  • Gestational diabetes. If you had gestational diabetes in one pregnancy, you’re more likely to have it again with the next pregnancy.


Type 1 diabetes can’t be prevented. But the healthy lifestyle choices that help treat prediabetes, type 2 diabetes and gestational diabetes can also help prevent them:

  • Eat healthy foods. Choose foods lower in fat and calories and higher in fiber. Focus on fruits, vegetables and whole grains. Eat a variety to keep from feeling bored.
  • Get more physical activity. Try to get about 30 minutes of moderate aerobic activity on most days of the week. Or aim to get at least 150 minutes of moderate aerobic activity a week. For example, take a brisk daily walk. If you can’t fit in a long workout, break it up into smaller sessions throughout the day.
  • Lose excess pounds. If you’re overweight, losing even 7% of your body weight can lower the risk of diabetes. For example, if you weigh 200 pounds (90.7 kilograms), losing 14 pounds (6.4 kilograms) can lower the risk of diabetes.But don’t try to lose weight during pregnancy. Talk to your provider about how much weight is healthy for you to gain during pregnancy.To keep your weight in a healthy range, work on long-term changes to your eating and exercise habits. Remember the benefits of losing weight, such as a healthier heart, more energy and higher self-esteem.

Sometimes drugs are an option. Oral diabetes drugs such as metformin (Glumetza, Fortamet, others) may lower the risk of type 2 diabetes. But healthy lifestyle choices are important. If you have prediabetes, have your blood sugar checked at least once a year to make sure you haven’t developed type 2 diabetes.

Lifestyle changes are the best way to prevent or delay the onset of type 2 diabetes.

To help prevent type 2 diabetes and its complications, people should: 

  • reach and keep a health body weight
  • stay physically active with at least 30 minutes of moderate exercise each day 
  • eat a healthy diet and avoid sugar and saturated fat
  • not smoke tobacco.

Associated Books

Download all biochemistry books for better understanding of diabetes


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