Hypoglycemia After Eating (Reactive, Postprandial) Causes, Symptoms, Diet

The intake of sufficient food ensures that our body has enough nutrition to sustain us for several hours. Even if a meal is missed, the body should be able to maintain adequate glucose levels to continue function at suitable levels. In fact the body maintains the glucose levels within a certain range, and even missing one or two meals would not cause these levels to drop below a certain point in a healthy person. When the blood glucose levels does drop below a minimum limit, it can affect proper physical and mental functioning.

What is reactive hypoglycemia?

Reactive hypoglycemia is also known as postprandial hypoglycemia. Postprandial means after eating while hypoglycemia means low blood glucose levels. Therefore postprandial hypoglycemia is where the blood glucose levels drop after eating. It is a result of an abnormality in insulin secretion and regulation. Overall hypoglycemia is not as common a condition as is often thought, and reactive (postprandial) hypoglycemia is even less common.

Symptoms that are typical of hypoglycemia like dizziness, shakiness, anxiety, hunger, nausea and irritability occur. In reactive hypoglycemia this occurs approximately 4 hours after a meal. This does not usually lead to a loss of consciousness but severe hypoglycemia, particularly in diabetics should be considered a medical emergency. However, a person may be unable to function properly in tasks that they are undertaking and need to eat/drink something and rest till the glucose levels stabilize. With reactive hypoglycemia, this is a result of eating contrary to the lack of food as is seen in fasting hypoglycemia.

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Reasons for Reactive Hypoglycemia

The healthy body can maintain glucose levels within a narrow range. Even if you eat very sweet foods, your blood glucose level will not exceed the upper limit. Similarly if you are fasting and do not eat for hours, the blood glucose level will not drop below the lower limit. Instead a healthy body can call up stores of glucose and even break down fat to sustain a relatively normal glucose level. However, people with hypgoglycemia do not have as efficient glucose control.

Fasting vs Reactive Hypoglycemia

Chronic hypoglycemia is not as common as chronic hyperglycemia (elevated blood glucose levels). The latter is seen in diabetes mellitus, type 1 or 2, with type 2 diabetes being one of the main chronic health conditions affecting middle-aged to senior adults. Hypoglycemia can be broadly divided into fasting hypoglycemia and reactive hypoglycemia. Fasting hypoglycemia is seen with several diseases or with using certain medication and occurs when a person has not eaten for a period of time.

Reactive hypoglycemia on the other hand occurs after eating. It is a result of insulin secretion that is normally at higher levels immediately after a meal persisting for hours thereafter. Insulin is the hormone responsible for lowering blood glucose levels when it is too high. However, it can drop blood glucose levels to abnormally low levels if there is not enough circulating glucose in the bloodstream. This is what occurs in reactive hypoglycemia.

Causes of Reactive Hypoglycemia

The cause of reactive hypoglycemia is not always known and in this case it is referred to as idiopathic reactive hypoglycemia. At other times the condition may be caused by problems in the alimentary tract or enzyme deficiencies from birth (congenital).

Alimentary Hypoglycemia

The alimentary tract is also known as the digestive tract. It starts at the mouth and ends at the anus, with most absorption of nutrients occurring in the small intestine. Alimentary hypoglycemia occurs in people who had surgery to the upper part of the tract like in gastrectomy or gastrojejunostomy. Glucose in the food is then absorbed too rapidly and excessive insulin is then secreted. Although uncommon, sometimes people with no prior history of alimentary surgery may develop alimentary hypoglycemia.

Congenital Enzyme Deficiency

This type of congenital enzyme deficiency is seen in people with hereditary fructose intolerance and galactossemia. It may also be seen with leucine sensitivity in children. With the body being unable to process the fructose and galactose due to a deficiency of the necessary enzymes, the accumulation of these substances then blocks the liver from releasing glucose. Leucine causes the secretion of excess insulin in response to a meal.

Risk Factors

Reactive hypoglycemia has been linked to being overweight or obese although it is an uncommon condition. It is more likely to occur in people with pre-diabetes (insulin resistance) or those who are at a high risk of developing diabetes. There may also be an overproduction of insulin due to certain tumors that produce insulin as well as the pancreas.

Symptoms of Reactive Hypoglycemia

The body requires an adequate and constant supply of glucose which sustains all cells in the body. Glucose is used for energy production that allows all the different types of cells in the body to continue with its respective functions. Insufficient glucose will then affect the normal functioning of cells. The brain tissue is by far the most sensitive to an inadequate glucose supply and will often react within minutes, and sometimes even seconds, to low levels of glucose in the bloodstream. Therefore the symptoms that are often first noticed are related to the brain. It includes:

  • Anxiety: agitated, uncharacteristically nervous.
  • Irritability: mood changes, bad mood.
  • Confused
  • Dizziness
  • Hunger
  • Shaky: unsteady, uncoordinated.
  • Perspires excessively.
  • Sleepy and tired.
  • Difficulty concentrating or performing mental tasks.

One or more symptoms may occur simultaneously. Some people also report nausea with sudden fatigue and sometimes a ‘funny’ taste in the mouth.

Treatment for Reactive Hypoglycemia

Ideally the root cause of the reactive hypoglycemia should be treated when identified and if possible. This may involve medication, surgery, dietary and or lifestyle changes targeted at the underlying condition that is causing the reactive hypoglycemia. Medication specifically to treat the hypoglycemia is not always started immediately. Instead it should be managed with dietary changes. Drugs known as alpha-glucosidase inhibitors can be useful in delaying glucose absorption but should only be considered in severe cases of reactive hypoglycemia where dietary management alone is insufficient.

Reactive Hypoglycemia Diet

Dietary management of restrictive hypoglycemia is very effective. It involves:

  • Stopping all refined sugars.
  • Eating more frequently in a day.
  • Reducing the meal size.

It is important not to exceed the daily calorie intake when eating more meals. Increasing protein and fiber intake may also be beneficial in slowing glucose absorption and helping to avoid the craving for refined carbohydrates. It is always advisable to consult with a registered dietitian/nutritionist to formulate an optimal eating plan for individual tastes, needs and the accessibility of relevant foods.

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