Diabetes is mainly classified into three types - type 1, type 2, and gestational diabetes, of which type 2 diabetes is the most common type of diabetes. Type 1 diabetes is caused by the lack of insulin due to the failure of the body to produce this hormone. On the other hand, type 2 diabetes is characterized by the inability of the body cells to use or respond to insulin. This is known as insulin resistance. Along with insulin resistance, insulin insufficiency can be associated with type 2 diabetes. Gestational diabetes is the condition that develops during pregnancy. Irrespective of the type, diabetes causes a rise in the level of blood sugar, which can ultimately affect several parts of the body, and cause a number of health problems.

The normal range for blood sugar level is less than 100 mg/dL when fasting, and less than 140 mg/dL two hours after having a meal. The effects of type 1 and type 2 diabetes on the body are more or less similar, as both the conditions increase the level of sugar in blood or cause hyperglycemia. In the long run, a consistently high level of blood sugar can affect the entire body. However, certain parts of the body are more likely to be adversely affected by this condition. The presence of excess sugar in blood makes the red blood cells stiff, which in turn, impairs the circulation of blood. It can also cause deposition of fats inside the blood vessels. It has been observed that the tiny and fragile blood vessels of the kidneys, eyes, and the feet are more likely to get damaged due to hyperglycemia. Untreated diabetes can affect the functions of the kidneys adversely, and cause diabetic nephropathy over a period of time. In nephropathy, the tiny blood vessels of the kidneys get damaged. High blood sugar levels make the kidneys filter more blood, and this extra workload can eventually take a toll on the kidneys and compromise their ability to filter blood. Hyperglycemia can also increase the levels of certain chemicals in the kidneys. These chemicals can make the tiny filters or glomeruli of the kidneys leaky. As a result, the affected individual starts losing proteins in urine. Additionally, hyperglycemia can cause cross-linking of proteins, which can cause scarring of the glomeruli. As a result, the kidneys fail to filter waste products effectively, which can eventually lead to kidney failure. The tiny and fragile blood vessels present in the retina can get damaged, if the level of blood sugar remains consistently high for a long period of time. The small capillaries of the retina can weaken and swell to such an extent that they collapse. Though new blood vessels do develop, most of them are defective, for which they fail to contain the leakage of blood and fluid. This can cause diabetes retinopathy, one of the many complications associated with uncontrolled diabetes. Moreover, diabetes can cause swelling of the lens, which can affect vision. Hyperglycemia can also cause blurred vision, and increase the risk of developing cataracts, glaucoma, and even blindness. Diabetes can significantly increase the risk of coronary artery disease, heart disease, and cardiovascular diseases in the long run. This condition can cause the deposition of fatty materials inside the wall of the blood vessels. This can clog the blood vessels and make them hard or stiff. This condition can eventually impair the circulation of blood through the blood vessels, and cause hypertension or high blood pressure, atherosclerosis, coronary artery disease, heart attacks, cerebral vascular disease, and strokes. Neuropathy or nerve damage is one of the most common complications associated with diabetes. The nerve damage associated with diabetes is known as diabetic neuropathy. The presence of excess sugar in the blood can damage the small blood vessels that supply blood to the nerves. The nerves present in the extremities of the body, such as the nerves of the legs, hands, and the feet are more susceptible to this condition. This condition can affect all peripheral nerves, as well as the autonomic nervous system. Diabetic neuropathy can produce several symptoms, like tingling and numbness in the legs, hands, and the feet, nausea, vomiting, diarrhea, urinary problems, constipation, and sexual dysfunction. People having diabetes are more likely to suffer from skin conditions like fungal and bacterial infections, along with bone and joint problems like osteoporosis. As mentioned already, high blood sugar levels can damage the nerves and the blood vessels, especially those present in the extremities of the body. This can eventually cause several foot problems, and loss of sensation in the feet. Even minor injuries to the feet, like blisters, sores, and cuts can become serious infections, as the supply of oxygen and blood to the feet can get disrupted. A severe infection can sometimes necessitate foot or leg amputation.