Glucagon initiates uptake of the stored glycogen in the liver into the bloodstream so as to increase glucose levels in the blood. Sporadic, high-carbohydrate snacks and meals are deemed the specific causes of sugar crashes. The “crash” one feels is due to the rapid increase and subsequent decline of blood sugar in the body system as one begins and ceases consumption of high-sugar foods. More insulin than is actually needed is produced in response to the large, rapid ingestion of sugary foods. Treatment
Reactive hypoglycemia can usually be relieved by dietary changes:
Avoiding or limiting sugar intake, including candy, sweet desserts, fruit juice, and drinks with added sugar. Eating only small amounts of starchy foods, including potatoes, pasta, breakfast cereals, and rice. Eating a variety of foods, including:
eggs, nuts, dairy products, tofu, beans, lentils, meat, poultry, fish, or other sources of protein with every meal or snack,
whole-grain carbohydrates, such as eating whole wheat bread instead of white bread, and
more fruits and vegetables (but not fruit juice), with 5 A Day being a recommended goal for most people. Eating more high-fiber foods, such as lentils, beans, pulses (legumes), leafy greens, and most fruits and vegetables.Other tips to prevent sugar crashes include:

Exercising regularly, as exercise increases cellular sugar uptake, which decreases excessive insulin release.
According to the U.S. National Institutes of Health (NIH), a blood glucose level below 70 mg/dL (3.9 mmol/L) at the time of symptoms followed by relief after eating confirms a diagnosis for reactive hypoglycemia. Signs and symptoms
Symptoms vary according to individuals hydration level and sensitivity to the rate and/or magnitude of decline of their blood glucose concentration.A crash is usually felt within four hours of heavy carbohydrate consumption. Along with the symptoms of hypoglycemia, symptoms of reactive hypoglycemia include:

The majority of these symptoms, often correlated with feelings of hunger, mimic the effect of inadequate sugar intake as the biology of a crash is similar in itself to the bodys response to low blood sugar levels following periods of glucose deficiency. Causes
The NIH states: "The causes of most cases of reactive hypoglycemia are still open to debate. Some researchers suggest that certain people may be more sensitive to the body’s normal release of the hormone epinephrine, which causes many of the symptoms of hypoglycemia. Others believe deficiencies in glucagon secretion might lead to reactive hypoglycemia.Several other hormones are responsible for modulating the bodys response to insulin, including cortisol, growth hormone and sex hormones. Untreated or under-treated hormonal disorders such as adrenal insufficiency (see also Addisons disease) or growth hormone deficiency can therefore sometimes cause insulin hypersensitivity, and reactive hypoglycemia. Stomach bypass surgery or hereditary fructose intolerance are believed to be causes, albeit uncommon, of reactive hypoglycemia.