Have you ever felt a powerful urge to sleep after a meal?
HEALTH The urge can be so strong that some people pass out right on the floor or drop their head on their desk at work. It sounds similar to a diabetic coma. Could it be hyperglycemia? Metabolically, what's going on?
For patients with diabetes, dangerously high blood sugar (hyperglycemia) or extremely low blood sugar (hypoglycemia) can lead to a diabetic coma. Thirst, fatigue, nausea and vomiting, shortness of breath, and increased heart rate signal hyperglycemia. A different set of symptoms is present for hypoglycemia. Diabetic patients must prevent either condition by abstaining from alcohol and monitoring food intake. 
While a sugar high is often associated with diabetes, it can also occur in people without this health condition. Have you ever heard someone say, "The blood rushes from your head to your stomach" after you eat?  Physiologically, there's a more going on.
Sugar or carbohydrate (which convert to sugar) overindulgence signals the increased production of insulin to neutralize to this sudden elevation in glucose. High levels of glucose and insulin trigger the release of adrenalin and cortisol. The heart may race and some people may feel a bit nauseous. [3,4]
Can Too Much Sugar Cause Diabetes?
Type 1 diabetes is caused by genetics and unknown factors that trigger the onset of the disease; type 2 diabetes is caused by genetics and lifestyle factors. Being overweight increases the risk for developing type 2 diabetes, and a diet high in calories, whether from sugar or from fat, can contribute to weight gain. Those with a family history of diabetes should eat healthy meals and regularly exercise to manage weight. 
Should I Avoid Carbohydrates?
Complex carbohydrates refer to the long complex chain of simple sugars found in the starchy foods. Although both types of carbohydrates – simple and complex – break down into glucose when digested by the body and are converted to energy in the cells, the metabolic process in complex carbohydrates is longer than in simple carbohydrates. The advantage of this slower rate of conversion of glucose to energy is that the release of energy is more sustained. Hence, unlike the simple sugars that quickly raise the blood sugar levels, complex carbs help maintain a stable glucose level in the bloodstream. 
How Can I Prevent Crashing From A Sugar High?
Balanced meals include the ideal ratio of 40-50 percent carbohydrates, 25-35 percent protein, and 20-30 percent fat.  Sometimes vegetarians have difficulty maintaing the proper balance when they forgo meat (protein) in favor of bread and pasta (carbohydrates). It is equally important to eat at regular times throughout the day. An irregular meal schedule slows the metabolism as your body stores more fat when it is uncertain when the next meal will be arriving. So avoid skipping meals and binging.
A good diet, an exercise regimen, and regular (nightly) sleep to regulate the circadian rhythm should minimize sugar crashes. Obtain a personalized nutritional guide  by using the online Healthy Body Calculator at dietitian.com. 
- Diabetic coma. mayoclinic.com
- Does blood rush to your stomach after eating? answers.com
- What Happens to Your Body When… You Carb Binge? marksdailyapple.com
- Epinephrine. wikipedia.com
- Diabetes Myths. American Diabetes Association, diabetes.org
- List of Foods With Complex Carbs. brighthub.com
- Caloric Ratio Pyramid. nutritiondata.self.com
- U.S. Department of Agriculture Food Nutrition. Low Carb List. healthandfitness.com
- Healthy Body Calculator® dietitian.com