Diabetes: Diagnosis and Types

Diabetes mellitus is a chronic metabolic disorder that affects our body's energy processes. After daily food intake, a large portion of nutrients is broken down into sugars (glucose), which are then transferred into the blood vessels. When sugar levels (blood sugar) exceed the set threshold, the pancreas kicks in. It releases the hormone insulin, the most important metabolic key to the entire energy process. This key hormone precisely controls the exact amount of glucose to be released into the blood. In diabetic patients, the pancreas is unable to produce enough insulin to regulate these glucose doses, which tend to rise uncontrollably in the blood. This leads to damage to the nervous, renal, and cardiac systems, as well as adverse effects on vision.

It is important to know that diabetes is not a contagious disease, that is, living with a diabetic patient does not cause you to contract it. It is not hereditary, in the sense that, with the exception of some very rare varieties (e.g. MODY), there is no possibility of transmission of the disease from generation to generation. However, there is a familial predisposition, more marked in the case of type 2 diabetes, so those who have a diabetic among their first-degree relatives (parents, siblings) have a higher risk of getting sick than those who have no relatives with the disease.

Diagnosis of diabetes

Diabetes is diagnosed in the following typical cases:

• Glycated hemoglobin (HbA1c) is greater than or equal to 6.5%.
• Blood sugar measured in the laboratory is equal to or greater than 126 mg/dl (in the morning, after 8 hours of fasting, in two circumstances).
• Blood glucose is equal to or greater than 200 mg/dL at the second hour after an oral glucose load (in two circumstances).
• Blood sugar is equal to or higher than 200 mg/dl at any time of the day in the presence of disorders (symptoms) typical of the disease (one circumstance is enough).

There are also conditions in which blood sugar levels are suboptimal and pose an increased risk of developing diabetes in the future. These conditions are diagnosed and defined as follows:

• Glycated hemoglobin between 6.00 and 6.49% (high risk of diabetes)
• Fasting blood glucose between 100 and 125 mg/dl (impaired fasting blood glucose)
• Blood sugar two hours after glucose ingestion between 140 and 199 mg/dl (glucose intolerance).

About one in five people with these conditions will develop diabetes within 5 years.

Types of diabetes

Diabetes is a rather complex disease, as it contains multiple clinical syndromes. It can be considered as a group of different diseases, united only by the fact that blood sugar levels are high.

The main varieties of diabetes are:

• Type 1 diabetes (also known as insulin-dependent diabetes) is autoimmune in origin and results from a relatively rapid destruction of the cells in the pancreas that produce insulin. This destruction is caused by substances (antibodies, cytokines) produced by the body's immune system cells, probably in response to a virus or one or more toxins present in the environment.
• Type 2 diabetes (also called non-insulin-dependent) develops over several years due to a deficiency in insulin production, which is, however, never as severe as that present in type 1 diabetes and is not dependent on autoimmunity. Multiple genetic alterations and acquired (environmental) factors are responsible for an insulin deficiency that is generally associated with reduced insulin effectiveness. Type 2 diabetes mainly appears after the age of 40, but the age of onset is decreasing due to the increasing prevalence of obesity, even in younger people.
• Gestational diabetes appears during pregnancy and usually disappears after delivery. Women who have had gestational diabetes are at risk of developing gestational diabetes again during subsequent pregnancies and type 2 diabetes later in life.
• Monogenic diabetes is a type in which there is a single genetic abnormality capable of causing a state of hyperglycemia. It is a type of diabetes that is transmitted from one generation to the next (a grandparent, a parent, and a child are affected) and appears earlier than type 2 diabetes, even though it shares many characteristics. A typical example is MODY (Maturity Onset Diabetes of the Young), of which there are many variants depending on the gene involved. This category also includes the very rare neonatal diabetes and other equally rare variants.
• In secondary diabetes and drug-induced diabetes , other diseases or medications cause impaired insulin secretion or effectiveness. Diseases that can cause diabetes include chronic pancreatitis, liver cirrhosis, chronic kidney failure, acromegaly, and Cushing's syndrome. Diabetes also develops when the pancreas is surgically removed. Diabetes, especially in predisposed individuals, can develop during prolonged treatment with cortisone or other medications.

As a collection of different diseases, each type of diabetes has unique symptoms, causes, and treatments.