Blood Sugar

Blood sugar

PKGhatak,MD

We need energy at all times just to stay alive and a higher rate of energy supply when we are engaged in activities. The lowest rate of energy requirement for an average person is 70 Kilocalories/hr. (Kcal); this is also called the Basic Metabolic Rate (BMR). The actual BMR varies according to height, weight, gender, age and ethnicity of the person and on the climate conditions.

The sugar that circulates in our blood is Glucose; table sugar is sucrose made up of one molecule each of glucose and fructose; milk sugar is lactose; a combination of glucose and galactose and fruits contain fructose. All sugars belong to a group called carbohydrates; also present in this group are- starch, dextrin, corn syrup, potatoes, wheat, cereal and rice. The body, for the most part, must break down starch and other sugars into glucose before turning glucose into energy. The human body is unable to break down cellulose, the most abundant carbohydrate in nature, the main constituent of trees and other vegetation. Cellulose provides the bulk of our daily meals.

As we eat food it gets mixed with saliva. Saliva contains an enzyme called Amylase and it begins to break down carbohydrates. The process continues in the stomach and in the upper small intestine where more amylase comes from the pancreas. As glucose is generated from other sugars and the breakdown of starch, it is picked up by the cells of the small intestine and then transported to the liver via blood. Any excess amount of glucose in the liver is converted into a complex glucose structure called Glycogen (commonly known as animal starch). The liver can easily turn glycogen into glucose and release it in circulation whenever there is a need. The muscles of our body store Glycogen as fuel for work.

Every living cell of the body has a chemical factory called Mitochondria. It is loaded with enzymes, catalysts, and a high-energy fuel packet called Adenosine Tri Phosphate (ATP). A chemical process called the Tricarboxylic acid cycle, better known as the Krebs cycle, is the main energy producing process in the body. We can view it as a furnace having three entry gates; one for the sugars, the other one for amino acids (derived from break down of proteins) and the third one for fatty acids (comes from fat). The products coming out of the Kerbs cycles are heat, ATPs, and other intermediate products. These intermediate products are in turn synthesized into fat, proteins, hormones, and other essential chemicals in the liver and other specific organs. Outside the mitochondria but within the cells, there is another process where glucose is directly converted into energy through a chemical pathway known as Hexose monophosphate shunt.

You must have known a friend or relative who would not add a grain of sugar in his coffee but at the same time drink two glasses of wine and finish half a bottle of ketchup over two hot dogs. They tend not to remember wine and prepared food containing carbohydrates. Yes, wine and drinks containing alcohol are carbohydrates. We eat about 300gm of carbohydrates on an average day; we need a minimum of 150 gm of carbohydrates daily in order to keep the chemical fire going in the body. When the minimum amount of carbohydrates is not present in the diet, the Krebs cycle will generate acetone from partially utilized amino acids and fatty acids. The human body cannot break acetone further. It is an acidic substance. It makes the cells sick and the kidneys work extra hard to eliminate acids. The appetite is lost and respiration becomes hurried. Over a period of time, the person loses weight. That is the basis of a high protein, low carbohydrate diet. It works for a short period of time but it is a different story a year or two later.

You must have noticed that in order to utilize sugar it must enter the cells first and then find its way to the mitochondria. In nature, nothing is left to a chance. The cell walls have pores, gates, binding sites, messengers, and controllers. Of these factors, Insulin is the most important member for glucose utilization. It is a hormone produced in the pancreas by Beta cells. If insulin is absent in the body or produced in less than normal amounts or the insulin is biochemically defective or antibodies against insulin making Insulin less effective. This will raise blood sugar levels in the blood. When the blood level exceeds the normal range, the condition is called Diabetes.

Normal blood sugar in the fasting state is less than 100 mg /100ml. When it exceeds 180 mg the sugar begins to show up in the urine. After a meal, depending upon the amount of carbohydrate ingested, the blood sugar may be anywhere from 100 to 180 mg/100 ml in normal individuals; in diabetics, it may be 200 mg or higher. In rare circumstances, the sugar may reach 1000 to 1200 mg /100ml.

The blood sugar may fall from having too much insulin in the body, from an insulin producing tumor or insulin administered inappropriately, or, in starvation or in conditions preventing a person from swallowing. When the level falls below 60 mg the person feels hungry, jittery, and tense and begins to sweat; when the level falls below 30 mg the person becomes confused and may behave in bizarre ways. In extreme cases of low sugar (hypoglycemia) unconsciousness, coma and death may follow.

Another hormone called Glucagon is produced by the alpha cells of the pancreas. Glucagon breaks down liver Glycogen into blood sugar and raises sugar levels.   Steroid hormones and adrenaline from adrenal glands are released in response to hypoglycemia and counteract some of these symptoms.

 

Normal blood sugar in an individual requires a balance between several hormones, insulin, food and a healthy gastrointestinal tract. In a diabetic individual, in addition to these, the level of physical activity is important also.

 

edited 2020.