The digestive system processes our food, breaking larger molecules down into their basic building blocks. Useful pieces are extracted and delivered to the bloodstream, and unused portions are eliminated as waste.
The body needs energy to use during daily activities. The body gets that energy when food is converted into glucose (a form of sugar) that is dumped into the bloodstream. 
When a person eats a meal, an organ called the pancreas secretes the hormone insulin. Insulin encourages cells to drink up the new sugar or glucose circulating in the blood. They can 

use it for energy, or store it to use later.

Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high. Blood glucose is your main source of energy and comes from the food you eat. Insulin, a hormone made by the pancreas, helps glucose from food get into your cells to be used for energy. Sometimes your body doesn’t make enough or any insulin or doesn’t use insulin well. Glucose then stays in your blood and doesn’t reach your cells. The accumulated sugar in the blood shows higher value and we are naming it as Diabetes.

What are the different types of diabetes?  
The most common types of diabetes are Type 1, Type 2, and Gestational diabetes.

Healthy Body  :  Blood Sugar normal level  
Normal blood sugar regulation. 
1  - After food enters the body,
2 - it is broken down and sugar enters the bloodstream.
3 - Sugar stimulates cells in the pancreas to release insulin.
4 - Insulin travels through the blood to other cells in the body and signals them to take up sugar 

When Cell Communication Goes Wrong
The cells in our bodies are constantly sending out and receiving signals. But what if a cell fails to send out a signal at the proper time? Or what if a signal doesn't reach its target? What if a target cell does not

does not respond to a signal, or a cell responds even

though it has not received a signal? These are just a few ways in which cell communication can go wrong, resulting in disease. In fact, most diseases involve at least one breakdown in cell communication.

When the Target Ignores the Signal

Type I and type II diabetes have very similar symptoms, but they have different causes. While people who have type I diabetes are unable to produce the insulin signal, those with type II diabetes do produce insulin. However, the cells of type II diabetics have lost the ability to respond to insulin. The end result is the same: blood sugar levels become dangerously high. ..read more