Reactive Hypoglycemia - Postprandial Hypoglycemia

Causes of Reactive Hypoglycemia: Unraveling the Underlying Factors

Hypoglycemia consists of an excessive drop in blood glucose levels to concentrations equal to or lower than 45-50 mg/dl.

When this deficit becomes particularly severe, hypoglycemia becomes a high-risk metabolic alteration; in fact, glucose represents the main energy substrate for the organism and in particular for the brain.

Not surprisingly, the deficiency of this sugar in the blood causes symptoms such as weakness, tachycardia, hunger with a craving for carbohydrates, nausea, anxiety, lack of muscular coordination, nervousness/irritability, mental confusion and sweating, up to hypoglycemic coma and death. .


Under normal conditions, severe hypoglycemia is a rare event, thanks to the intervention of automated neuroendocrine responses (reduction in insulin synthesis and increased release of glucagon, catecholamines, cortisol and GH); furthermore, hypoglycemia pushes the subject towards seeking food, preferably carbohydrates, which quickly restores glycemic levels to normality.

Excess insulin

Hypoglycemia is typical of diabetes treated with excessive doses of insulin or oral hypoglycemics, but it can occur – in a mild form – even in healthy patients, for example due to too prolonged fasting or intense and prolonged physical effort.

Reactive hypoglycemia

A particular shape, called reactive or postprandial hypoglycemia, typically occurs after meals, often two or three hours after their completion. Most of the time the cause of this condition remains unknown. In this regard, various hypotheses have been formulated; the first is that individuals affected by reactive hypoglycemia are too sensitive to adrenaline, a hormone – renamed stress – which produces symptoms similar to those caused by hypoglycemic crises, and whose release is favored by hypoglycemia. Another hypothesis is that these subjects do not produce sufficient quantities of glucagon, a hormone that opposes the excessive drop in blood sugar by counteracting the actions of insulin. Not surprisingly, reactive hypoglycemia can also be caused by hyperinsulinemia, or hypersecretion of insulin by the pancreas; not infrequently, this condition is accompanied by late hypoglycemia (after the fourth hour after the end of the meal).

At a medical level, impaired glucose tolerance accompanied by hyperinsulinemia is considered a prediabetic state, with possible and probable evolution to full-blown diabetes mellitus. This is also why reactive hypoglycemia is typical of the early stages of type II diabetes mellitus; in patients who are affected, hyperglycemia is recorded after the meal linked to a delay in insulin secretion, which is insufficient in the first hours and excessive in the following ones.

Other Causes of Hypoglycemia

At the basis of reactive hypoglycemia there may be congenital enzyme deficiencies, such as hereditary fructose intolerance, galactosemia and leucine sensitivity in newborns (amino acids also stimulate the release of insulin).

Another cause of reactive hypoglycemia is represented by gastro-resection surgeries to which, for example, obese people or people with stomach cancer are subjected; this condition, just like the congenital hypervelocity of gastric emptying, determines a rapid arrival of the chyme at the level of the small intestine (which in normal conditions receives it extremely gradually) and an equally rapid absorption.

Role of Medicines and Foods

There are drugs (such as acarbose), supplements (psyllium, guar gum, pectin) and in general foods rich in fibre, which act in the opposite direction and which therefore – by slowing down the intestinal absorption of glucose – can prove useful in prevention of reactive hypoglycemia.

On the contrary, the ingestion of alcohol in large quantities, especially in chronic alcoholics in a state of malnutrition, favors reactive hypoglycemia, probably due to the depression of gluconeogenesis induced by its metabolization.

Role of Diet

A meal particularly rich in simple carbohydrates (sugars), such as a feast of sweets, represents a faithful ally of reactive hypoglycemia. The rapid entry into the bloodstream of glucose absorbed by the intestinal mucosa stimulates a strong pancreatic release of insulin, necessary to bring blood sugar levels back to normal which have become dangerously high.

Thus, in the healthy individual, glucose enters forcefully into the cells, with a rapid decrease in its blood concentrations; we are therefore talking about reactive hypoglycemia, a condition which, as we saw at the beginning of the article, stimulates the hypothalamic hunger centre. Hence, the recommendation to reduce the consumption of simple sugars and increase that of fresh vegetables, valid both for slimming diets (increases the sense of satiety, reduces bulimic crises), and in the preventive context, against pathologies related to diabetes and overweight.

Behavioral tips to prevent reactive hypoglycemia:


The diagnosis of reactive hypoglycemia can be made on the basis of the results of the OGTT, the “famous” oral glucose load test. In this test, an aqueous solution of approximately 75 grams of glucose is administered orally, recording the glycemic values ​​(and possibly insulin values) at pre-established time intervals (30′, 60′, 90′, 120′, 150′, 180 ‘, 210′, 240′, 270′ 300’). The diagnosis is certain if blood sugar levels fall below 45 mg/dL, while it is probable if the minimum blood sugar levels are between 45 and 55 mg/dL. The test allows, among other things, to diagnose diabetes and impaired glucose tolerance, positive if glycemic levels rise above 139 and 199 mg/dL 180 minutes after ingestion of the solution, respectively.

To know more:
Drugs for the treatment of reactive hypoglycemia


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