notes by dr Claudio italiano
It all started by chance, studying the saliva of a lizard, the Gila Monster,
a desert reptile that eats only a few times a year, with frightening glycemic
spurs, as a result of which the blood sugar, as a miracle, returns to normal
values. The scientists, intrigued by the thing, isolated the exedin 4 from its
saliva from which the exenatide was obtained, a pharmacological substance
ascribed to the group of incretins (see incretine incretine_2) that mimics the
action of GLP1. Today we have the first numbers, who writes to you has had
excellent care experiences using the incretins (gliptins and exenatide),
associated with therapies such as metformin and glitazones. In fact, after some
time the diabetic patient sees his glycata reduced to 5.5 or less! Then there
are those that have lower benefits and for which it is necessary to begin to
associate slow analogue insulin and / or others that benefit only from the
therapy with mimics of GLP-1 (read GLP one). In short, it was the discovery of
hot water, so to speak, but that has given a breakthrough in the history of
diabetes treatment, just as glycosines are doing for now, reversing the notion
that glycosuria is a bad thing. They said a sensational discovery, which finally
showed that a hormone, freed from an intelligent intestinal tube, collaborates
with the pancreas and launches powerful signals for good diabetes care.
The story of the incretine begins in 1930, with the definition of "incretina",
that is Intestine Secretion Insulin, but it must arrive to 1960 to have the
pharmacological confirmation of the action of the same; in 1970 we talk about "enteroinsular
axis" "and we discover the product of the proglucagon gene in the 80s. But we
must get to the 90s to use these new peptides for pharmacological purposes in
the treatment of type 2 diabetes.
It is the physiological insulin response to a glucose load per os that is greater than the administration of glucose into a vein; that is, the intake of sugars by the oral route, therefore physiological, gives a greater insulinemic response. Now, in order for it to take place, there are a series of modifications within the pancreatic beta cell; first, the potassium channels are blocked, creating a potential difference within the cell that allows the opening of calcium channels and the granulation of insulin granules. But what is most interesting today's diabetologist is the trophic action that is practiced on the beta cell, as demonstrated on the Goto-kakizaki mice, where the drug activates the multiplication of beta-cells.
See the photo below.
Basically GLP1 is a sort of lookout, produced by cells of the digestive tract,
which as soon as it sees that they drink or eat carbohydrates, signals to the
pancreas the need for a ready secretion of insulin. It is not the usual action
of the so-called "secretagogues" drugs, that is, those who, as it were, "squeeze
the pancreas like a lemon, as long as there is juice, but of smart hormones that
carry a signal, which, as we said, is that of the tropism of the pancreatic beta
cell. Glp-1 is very interesting because it acts at different levels preparing
the organism to absorb the incoming glucose with the ingestion of the meal. The
beta-cells that produce insulin in the pancreas normally increase the production
as soon as the blood sugar begins to increase. Indeed, the release of insulin
precedes the increase in blood sugar thanks precisely to the Glp-1.
Early-warning systems such as Glp-l in diabetes function poorly. Insulin
production did not immediately 'start' or 'do it insufficiently, and it also
increases the production of glucagon (which raises blood sugar and that Glp-l
should reduce). As a result of these mechanisms, the blood glucose rises
excessively after the intake of the meal, resulting in those blood glucose peaks
that patients with diabetes know well and fear. Glp-1 also acts on the stomach
slowing down, slowing digestion. This is important for maintaining a proper
glycemic balance, because carbohydrates should be gradually metabolized by the
intestine, slowing down the gastric emptying, making the transformation of
carbohydrates into glucose in the blood more gradual. Furthermore, the early
feeling of a full stomach causes one to feel full before. Glp-l also has an
effect on the centers that in the brain generate or delay the feeling of satiety,
favoring a lower introduction of calories and therefore facilitating weight
loss. In short, restoring a good functioning of the Glp-l results are obtained
in terms of both the reduction of glycated hemoglobin and weight. We speak on
average, a loss of 3-5 pounds which tends to remain if not even increase over
time
Precisely for this reason their tolerability is very good. The first advantage
of course is the improvement of blood sugar levels which on average results in a
reduction of about one percentage point of glycated hemoglobin. As mentioned,
for their particular mechanism of action. the incretins have a particular effect
in reducing postprandial hyperglycemic peaks which seem to have specific
independent effects on the risk of complications of the diabetic patient.
Secretagogues stimulate the beta-cell to produce insulin as a function of
glucose levels: so much insulin for high blood sugar levels, little insulin or
nothing if blood sugar levels are normal or low. There is therefore no risk of
hypoglycemia. Those who have had a serious hypoglycemia often fear
to repeat the negative experience that he experiences as a loss of control over
himself). Finally, a 'glu' effect of Glp-l on the pancreas is documented. In the
natural history of type 2 diabetes there is a gradual reduction in the number of
betacellulae. It is also for this reason that the treatment, with the passage of
time, must be intensified. Diabetes seems to worsen.
If these data were also confirmed in humans, acting on the incretin system we
could be able to slow down, or in some cases to reverse this phenomenon by
witnessing episodes of regeneration of beta cell mass. The Glp-l has a very
short average life. Within a couple of minutes the Glp-l secreted from the
intestine is destroyed by an enzyme called DPP IV. To guarantee the therapeutic
levels of Glp-l, scientific research has undertaken three ways producing:
- Analogs of Glp-1: molecules of Glp- slightly modified to allow adhesion to the
blood proteins and therefore make them resistant to the action of Dpp-4.
- Glp-1 receptor agonists: widely modified Glp-l molecules,
capable of activating endogenous Glp-I receptors, mimicking their effects.
- Gliptins or Dpp-4 inhibitors: enzymes that prevent the action of Dpp-4
allowing the Glp-l produced by the intestine to remain in circulation for longer.
Gliptins are administered orally, while Glp-l analogues and agonists are
injected into the subcutaneous tissue. The receptor agonist is injected twice a
day, whereas the Glp-1 analog requires only one injection per day. The future
promises even more sparse injections (weekly).
The goal of pharmacologists is to achieve the same effects by minimizing the
number of 'bites', (these efforts are welcome because anything that can meet the
patient's real or perceived needs is an advantage, but I think the psychological
resistance of the patient is easier to overcome than I can
to seem. The results in terms of weight and glycemia are - especially at the
beginning - fast and visible so much that when I thought about prescribing these
injections only for a short time, I had difficulty in removing them,
Like many drugs, these can also have clinically insignificant but subjectively
unpleasant effects.
Glp-1 is a naturally produced hormone from the intestine and insufficiently
released in the person with diabetes. Glp-l prepares the organism to receive
carbohydrates by acting on four levels:
• Pre-warning the pancreatic beta cell so that it prepares itself to produce a
sufficient amount of insulin
• Pre-warning the pancreatic alpha cell so that glucagon production is reduced
and the liver stops releasing glucose into the blood
Slowing down the digestion process so that the transit of carbohydrates in the
intestine is gradual
• Activating the satiety centers in the brain, Glp-1 has a very short average
life:
a few tens of minutes, because quickly destroyed by the enzyme Dpp IV.
In order to guarantee sufficient levels of this important hormone in the blood,
the therapies provide:
• Enzyme inhibitor pills that destroy Glp-1 preserving it in circulating
gliptins
• Injection of substances similar to Glp-l [agonistsJ which resist the
destructive action of Dpp-4 and mimic the action of Glp-t
• Injections of the manipulated Glp-t so that it binds to the circulating
proteins and protects it from destruction by the Dpp_4.
In the near future, injections of Glp-l analogues may be given once a week.