Overview of Diabetes type 1 and type 2 < PREVIOUS

Causes

Causes are very different for each case as diabetes is a group of diseases that share the same outcome : high blood sugar. As the process of blood sugar control  is complex and involves many steps, anything that goes wrong at any step would result in the disease (Fig. 1).

Fig. 1: Type 1 and 2 diabetes. In healthy people (upper panel), pancreas produces enough insulin, insulin binds to receptor on target cell and induces glucose intake. In type 1 diabetes (middle panel) insulin production is reduced, less or no insulin binds to receptor, glucose stays outside target cell (in the blood). In type 2 diabetes (lower panel) pancreas produces enough insulin but something goes wrong either with the receptor binding or insulin signaling in the target cell, glucose stays outside the cell (in the blood). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 Causes of type 1 diabetes: In type 1 diabetics, beta cells of the pancreas are destroyed by the immune system by mistake – autoimmune disease (Fig.2). The reason why this happens is unclear, but genetic factors are believed to play a major role.

Fig. 2: Anatomy of a pancreatic islet showing beta cells selectively destroyed in type 1 diabetes. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

Causes of type 2 diabetes: These are more diverse as there are many steps that could possibly go wrong. In some cases, beta cells are dysfunctional and produce a modified version of insulin that can no longer bind to its receptor. In other cases, the problem lies within insulin receptor or in the downstream signaling in target cells. The common hallmark is the normal level of insulin in the blood. Here again, genetic factors predispose susceptibility to the disease, but it’s believed that lifestyle plays a very important role. Typically, obesity, inactive lifestyle, and unhealthy diet are associated with higher risk of type 2 diabetes. 

Causes of gestational diabetes: hormonal changes during pregnancy, notably the presence of placental hormone lactogen, may interfere with insulin receptor on target cells and make them less responsive to insulin. This occurs in about 5 to 10% of all pregnancies, more commonly during the third trimester, and if left untreated, may progress to type 2 diabetes.

Symptoms

Type 1 symptoms tend to come sudden, quickly, type 2 symptoms may develop over a long period of time. The earliest signs of diabetes are excessive thirst, frequent urination, then come excessive hunger, fatigue, weight loss, high blood pressure, blurred vision, frequent infections (especially in the skin, genitals, bladder). Long term untreated diabetes may lead to other complications including vascular diseases (heart attack, stroke), nerve damage (most commonly loss of feeling in the feet), kidney damage, diabetic coma,…