What is Diabetes Mellitus?

Diabetes is a chronic disease that occurs either when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces. Insulin is a hormone that regulates blood sugar. Hyperglycemia, or raised blood sugar, is a common effect of uncontrolled diabetes and over time leads to serious damage to many of the body’s systems, especially the nerves and blood vessels. In 2014, 8.5% of adults aged 18 years and older had diabetes. In 2016, diabetes was the direct cause of 1.6 million deaths and in 2012 high blood glucose was the cause of another 2.2 million deaths. In general Diabetes can be categorized into:
1. Chronic diabetes conditions include:
a) Type 1 diabetes
b) Type 2 diabetes.
2. Potentially reversible diabetes conditions include:
a) Pre-diabetes: when your blood sugar levels are higher than normal, but not high enough to be classified as diabetes
b) Gestational diabetes: which occurs during pregnancy but may resolve after the baby is delivered

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. type1 diabetes is not preventable with current knowledge.
Symptoms include excessive excretion of urine (polyuria), thirst (polydipsia), constant hunger, weight loss, vision changes, and fatigue. These symptoms may occur suddenly.
Causes of type 1 diabetes
The exact cause of type1 diabetes is unknown. What is known is that your immune system — which normally fights harmful bacteria or viruses — attacks and destroys your insulin-producing cells in the pancreas. This leaves you with little or no insulin. Instead of being transported into your cells, sugar builds up in your bloodstream.
Type1 is thought to be caused by a combination of genetic susceptibility and environmental factors, though exactly what those factors are is still unclear. Weight is not believed to be a factor in type 1 diabetes.

Type2 diabetes
Type2 diabetes (formerly called non-insulin-dependent, or adult-onset) results from the body’s ineffective use of insulin. Type2 diabetes comprises the majority of people with diabetes around the world, and is largely the result of excess body weight and physical inactivity.
Symptoms may be similar to those of type1 diabetes, but are often less marked. As a result, the disease may be diagnosed several years after onset, once complications have already arisen.
Until recently, this type of diabetes was seen only in adults but it is now also occurring increasingly frequently in children.

Causes of Type2 diabetes
Type 2 diabetes develops when the body becomes resistant to insulin or when the pancreas is unable to produce enough insulin. Exactly why this happens is unknown, although genetics and environmental factors, such as being overweight and inactive, seem to be contributing factors.

(Pre-diabetes ) 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 type2 diabetes, although this is not inevitable.

Causes of pre-diabetes and type2 diabetes
In pre-diabetes (which can lead to type 2 diabetes) and in type2 diabetes, your cells become resistant to the action of insulin, and your pancreas is unable to make enough insulin to overcome this resistance. Instead of moving into your cells where it’s needed for energy, sugar builds up in your bloodstream.
Exactly why this happens is uncertain, although it’s believed that genetic and environmental factors play a role in the development of type2 diabetes too. Being overweight is strongly linked to the development of type2 diabetes, but not everyone with type2 is overweight.

Gestational diabetes
Gestational diabetes is hyperglycemia with blood glucose values above normal but below those diagnostic of diabetes, occurring during pregnancy.
Women with gestational diabetes are at an increased risk of complications during pregnancy and at delivery. They and 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.

Causes of gestational diabetes
During pregnancy, the placenta produces hormones to sustain your pregnancy. These hormones make your cells more resistant to insulin.
Normally, your pancreas responds by producing enough extra insulin to overcome this resistance. But sometimes your pancreas can’t keep up. When this happens, too little glucose gets into your cells and too much stays in your blood, resulting in gestational diabetes.

What are common consequences of diabetes?
Over time, diabetes can damage the heart, blood vessels, eyes, kidneys, and nerves.
1. Adults with diabetes have a two- to three-fold increased risk of heart attacks and strokes.
2. Combined with reduced blood flow, neuropathy (nerve damage) in the feet increases the chance of foot ulcers, infection and eventual need for limb amputation.
3. Diabetic retinopathy is an important cause of blindness, and occurs as a result of long-term accumulated damage to the small blood vessels in the retina. 2.6% of global blindness can be attributed to diabetes.
4. Diabetes is among the leading causes of kidney failure.