Generality
Postprandial blood glucose is a numerical value that indicates how much glucose is present in the blood two hours after the end of a meal.
At a distance of 60-120 minutes from the end of a substantial meal (abundant breakfast, lunch or dinner) the blood sugar levels record the maximum peaks of the day. This phenomenon, absolutely normal within certain limits, is linked to the entry into the circulation of glucose deriving from the digestion of glucidic foods and absorbed in the intestine.
Postprandial blood glucose is controlled by insulin secreted by the pancreas, in order to favor the entry of blood glucose into cells, which use it for energy purposes or transform it - especially at the liver level - into a metabolic reserve (in the form of glycogen and / or or triglycerides).
Thus, in healthy people, postprandial glycemic levels rarely rise above 140 mg / dl (7.8 mmol / l), and then return to baseline levels within 3-5 hours of food intake.
Postprandial hypoglycemia, in-depth article.
Health hazards
In people with manifest diabetes or in a state of reduced glucose tolerance (IGT), the mechanism described above does not work properly. As a result, postprandial blood sugar rises above levels considered normal, trespassing the pathological.
Over time, the recurrence of postprandial hyperglycemic phenomena ends up damaging the eyes, kidneys, nerves and blood vessels. In particular, a high postprandial blood sugar level is related to the development of diabetes complications, both type one and second type. Among the most serious are neuropathy, renal insufficiency, vision loss, macrovascular diseases and amputations. Until a few years ago the prevention of these complications, and the therapy of diabetes itself, have mainly focused on the reduction of HbA 1c levels (glycated hemoglobin) and on the control of fasting plasma glucose. Today, however, the treatment is also aimed at reducing post-prandial glycemic excursions, considered equally important - if not even more important - for achieving an optimal glycemic control and for the prevention of complications, especially of a macrovascular nature. The latter are responsible for the net increase in mortality due to pathologies such as myocardial infarction and stroke compared to the healthy population.
The World Health Organization defines normal glucose tolerance as glucose values below 140 mg / dl (7.8 mmol / l) two hours after ingestion of a 75 g glucose load, in the context of an oral test glucose tolerance. In these guidelines, postprandial hyperglycemia is defined by levels above 140 mg / dl (7.8 mmol / l) two hours after food ingestion.
Postprandial hyperglycemia begins before type 2 diabetes, when the patient is still in a pre-diabetic state, defined as impaired glucose tolerance.
How do you measure it?
Treatment
What to do to decrease postprandial blood glucose levels
Nutritional interventions, physical activity and body weight control are the cornerstones of effective diabetes management, also from a preventive standpoint.
As stated in the previous chapter, the purpose of these interventions - possibly assisted by specific pharmacological therapies - is to achieve optimal glycemic levels, not only on an empty stomach (<100 mg / dl or 5.5 mmol / l) but also in the post-stage prandial (<140 mg / dl or 7.8 mmol / l).
Low glycemic index (GI) diets benefit the control of postprandial plasma glucose. These dietary strategies are based on the prevalent consumption of foods rich in fiber (vegetables, legumes and non-sugary fruit), as opposed to the moderation of foods rich in complex carbohydrates (al dente pasta, rice, whole wheat bread, baked goods and cereals in general, potatoes, tubers, chestnuts) and the avoidance of simple sugars (sucrose, white bread, honey, sweets, snacks, sweetened drinks etc.). However, in the practical application of the glycemic index, the concept of glycemic load should not be forgotten, given by the product between the carbohydrate content of the diet and its average GI. It is therefore necessary to focus both on the choice of carbohydrates with a lower glycemic index, and on the quantitative moderation of the same.
Various pharmacological agents preferentially reduce postprandial plasma glucose. To this category belong α-glucosidase (acarbose) inhibitors, glinids (fast-acting insulin secretagogues) and naturally insulin (fast-acting insulin analogues, biphasic insulin [premixed], inhaled insulin, insulin regular human). Furthermore, new therapeutic classes for the treatment of postprandial plasma glucose in diabetic patients - among which we mention amylin analogues, glucagon-like peptide-1 derivatives [GLP-1] and dipeptidyl peptidase-4 inhibitors [DPP -4] - have been shown to bring significant benefits in reducing glycemic excursions after meals. These therapies control fasting and postprandial glycaemia by acting on pancreatic and intestinal hormone deficiencies, which affect the secretion of insulin and glucagon, the feeling of satiety and gastric emptying.
