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Diabetes is a condition of our body in which the quantity of glucose present in our blood rises above the safely tolerable level, and casues damage to vital organs of the body like, heart, Brain, Blood vessels, Kidneys, Nerves etc.

This happens due to the relative deficiency of the hormone Insulin , a hormone secreted by pancreas .

In order to function or body requires energy( just as our cars need gas or petrol to run, or bulbs and eletrical appliances require electricity to be switched on). The enegry requirements of our body are continous- even though we might be sleeping- the heart is still pumping ( its muscles are contracting, thus they need energy to work), the brain is still functioning (all the neurons in brain need continous supply of energy), Breathing-inhalation and exhalation - are also continous processes which keep on happening and require energy. Energy for all the processes is derived to a large extent from glucose and fats circulating in the blood.
The Dilemma is that even though we use energy continously we acquire it only with food, which we generally take only few times a day. Our body has inbuilt mechanisms which provide us with uninterrupted energy supply. Whenever we eat food, the ingested vital constituents like glucose, fats (free fatty acids) and proteins in form of amino acids are stored inside the body and later released into circulation when required.
The hormone Insulin plays a very important part in regulation and coordination of energy supply during the periods of fasting ( energy supply) and after ingestion of food (energy storage) .

Some main effects of Insulin in this context are:


One of the important effects of insulin  is glucose utilization.

Generally whenever we eat or drink something except plain water, there is always some glucose contained in it ( Remember just like sugar free sweeteners- their are sugars which may actually not be sweet!!) As the glucose contained in ingested food or drinks crosses over from the Gastro- intestinal ( Mouth-Stomach-intestines) tract to blood the level of sugar in blood starts to rise. In response to the high level of blood sugar, some immediate changes take place, including release of insulin into blood stream by Pancreas. Insulin decreases the blood sugar levels as they rise immediately after ingestion of meals or formation and release of glucose inside the body itself from different raw materials.
Actually as the blood rich in sugar is flowing past the cells ( More so in some specialized cells of Liver, Muscles, Fat etc.) there are special sensors on the cell walls which detect the presence of insulin. If they come in contact with insulin molecule they double as receptors or keyholes for insulin, in which it fits in akin to a key fitting and turning inside a lock, this causes a whole chain of events inside the cell. These events further result in opening of the gates which allow glucose present in the blood to enter the cell and get stored there ( like selectively allowing only some people to enter through your frontdoor and letting them stay inside).
Even though glucose enters the cell even in absence of insulin,  the rate of uptake of glucose into the cells is increased by 10-20 times in the presence of insulin. Insulin also facilitates further processing and utilization of glucose by the cells.
muscle_trp1Glucose is stored in Liver and muscles in the form of glycogen, after the absorption of the meal e.g liver_trp during sleep or periods of intense exercise, glycogen is converted into glucose and released into blood circulation from liver or utilized by muscles.
Another source of glucose in blood is conversion of Fats and Proteins to glucose- this process is called gluconeogenesis, it happens in liver and to a smaller extent kidneys.
All the above mentioned processes involving storage and release of glucose into blood from different organs is intricately controlled by insulin.

The deficiency of insulin may be both in quantity or quality or insulin may be altogether absent as well.

Body's mechanism for sensing of blood glucose, fats and proteins and its energy needs is very complex. Any malfunction at any level (e.g Blood glucose sensing, Release of insulin, Sensing of the insulin, uptake by the cells of insulin, Action of insulin inside the cells) may result in deranged capability of body to maintain normal blood glucose levels. In any patient at any time a single or multiple defects may be present.

Complete absence of insulin takes place in Type 1 Diabetes Mellitus or so called Insulin Dependent Diabetes, in this disease the body does not make any insulin at all due to the destruction of _-cell islets in Pancreas, which make and release insulin into blood. People suffering from this disease require life long insulin injections.

In the other type of diabetes  Type 2 Diabetes Mellitus Insulin is being made and released by the pancreatic b islet cells but either it is not sufficient in quantity or there is decreased effect of the same insulin which may be due to any cause- either poor quality of insulin or some impairment in its recognition and processing by the cells.

AMERICAN DIABETES ASSOCIATION