Diabetes

Diabetes, is the most well-known metabolic disease that can affect humans.

Its onset is linked to insulin; To be precise, it may depend on a reduced availability of insulin (the production of which does not meet the body's needs), poor sensitivity to the hormone by the target tissues or, finally, a combination of these factors.

A clinical feature of diabetes is hyperglycaemia, which results from the above-mentioned insulin abnormalities.

Currently, the medical-scientific community recognizes the existence of three major types of diabetes mellitus, which are: type 1 diabetes, type 2 diabetes and gestational diabetes

Diabetes mellitus, or more simply diabetes, is a metabolic disease resulting from a decrease in the activity of insulin, a hormone produced by the beta cells of the islets of Langerhans of the pancreas.
In particular, diabetes can be due to:

• Reduced insulin availability: there is less insulin than the body would need for its proper functioning;

• An impediment to the normal action of insulin: insulin is present, but the body cannot make good use of it;

• A combination of the two factors mentioned above: insulin is low and does not work properly.

An ever-present feature of diabetes mellitus is hyperglycemia (high concentration of glucose in the blood), which, over time, tends to be associated with vascular complications, such as:

• Macroangiopathy (a particularly severe and early form of atherosclerosis),

• Microangiopathy (an alteration in blood circulation within the small arterial vessels, manifested mainly in the retina, kidney and nerves).

While microangiopathy is specific to the pathology in question, macroangiopathy is not.

Types of diabetes

Internationally recognized, the classification of diabetes mellitus drawn up in 1997 by the WHO and the ADA divides diabetes into three main types:

• Type 1 diabetes mellitus: this includes almost all immune-mediated diabetic forms; in these circumstances, the underlying cause is a malfunction of the immune system, which, recognizing the pancreatic beta cells of the islets of Langerhans as foreign, attacks and destroys them.
  Because the immune system is involved, type 1 diabetes mellitus is an autoimmune disease.

• Type 2 diabetes mellitus: this includes all forms of diabetes, due to a deficiency in insulin secretion by pancreatic beta cells of the islets of Langerhans, and a resistance of the body's tissues to the action of insulin (a condition known as insulin resistance).

• Gestational diabetes: this includes forms of diabetes secondary to pregnancy. Typically, it is a transient phenomenon.

Prediabetes

As mentioned above, by definition, diabetes mellitus is characterized by hyperglycemia.

To determine the presence of hyperglycemia – and establish whether or not there is diabetes – a venous blood sample is taken and the amount of glucose present is then measured on this blood sample.

According to the latest criteria proposed by the ADA experts, a person suffers from diabetes when the following three conditions are met:

• Blood glucose (i.e., the concentration of glucose in the blood) is ≥ to 11.102 mmol/L (200 mg/dl) at any time of the day.

• Fasting blood glucose is ≥ to 6.994 mmol/L (126 mg/dl).
  Under normal conditions, it should be less than 5.551 mmol/L (100 mg/dl).

• Blood glucose after 120 minutes of oral glucose tolerance test or oral glucose load test) is ≥ to 11.102 mmol/L (200 mg/dl).
  Under normal conditions, it should be less than 7.771 mmol/L (140 mg/dl).

The need to define such precise parameters, to establish when a person has diabetes or not, arose when doctors and experts identified the existence of an intermediate metabolic state between normal and type 2 diabetes mellitus, to which they assigned the name of prediabetes.

Prediabetes is a condition that often precedes the onset of full-blown type 2 diabetes mellitus; Therefore, its identification should sound like an alarm bell.

Those who suffer from prediabetes do not have the same symptomatic picture as the person with diabetes and often do not even have a symptom of the latter; However, like the diabetic subject, he has abnormal blood sugar levels, higher than normal.

According to the ADA and WHO, there are two subtypes of prediabetes: the subtype called impaired fasting blood glucose or IGF and the subtype called impaired glucose tolerance or IGT.

• Impaired Fasting Blood Glucose

To make a diagnosis of impaired fasting blood glucose, it is necessary to find, after at least 8 hours of fasting, blood glucose levels that are higher than normal, but not high enough to fall into a state of diabetes.

• Impaired Glucose Tolerance

On the contrary, in order to make a diagnosis of impaired glucose tolerance, it is necessary that the blood glucose, after the so-called oral glucose tolerance test, is between 7.771 mmol/L and 11.102 mmol/L (140  and 200 mg/dl) (in essence, it is higher than the normal threshold, but below the limit that establishes the presence of diabetes).

The ADA explain that prediabetes is not to be considered a true clinical entity, but rather an increased risk of diabetes and cardiovascular disease, and it is associated with obesity it usually does not involve symptoms; The only clinical sign is a high amount of sugar in the blood.

Diabetes insipidus

In addition to diabetes mellitus with its two types, there is another form of diabetes: the so-called diabetes insipidus.

Except for excessive diuresis and insatiable thirst, diabetes insipidus is completely different from diabetes mellitus and is in no way related to the latter. In diabetes insipidus, in fact, the problems in progress do not revolve around increased blood glucose levels (following a drop in insulin activity), but depend on a lack or insufficient production of the hormone vasopressin (or ADH or antidiuretic hormone) or on its lack of activity in the kidneys.

Quickly summarizing, therefore, the condition of diabetes insipidus can set in because:

• Hypothalamus and posterior pituitary gland do not produce vasopressin at all

or

• The hypothalamus and posterior pituitary gland produce insufficient amounts of vasopressin to meet the needs of the human body

or

• Vasopressin does not perform its activities adequately in the kidneys. Vasopressin has the important task of keeping the liquid part of the blood (the so-called plasma) constant; To accomplish this task, it acts at the kidney level, where it promotes the reabsorption of water and opposes the production of urine (hence the name antidiuretic hormone).

When vasopressin production is absent or insufficient, diabetes insipidus is called central, ADH-sensitive, or neurogenic; when, on the other hand, vasopressin is present but has no effects on the kidneys, diabetes insipidus is called ADH-insensitive or nephrogenic.