question: How does diabetes lead to so many other issues?
comment: It's mostly through damage to blood vessels caused by high blood glucose. High sugar blood causes damage and breakdown of blood vessels, they don't like it. So in the eyes, the blood vessels break down causing leakages into the eye and extra blood vessels being formed. The result is a loss of vision. The kidneys are also very vascular, lots of blood vessel damage = a deterioration in renal function. The kidneys don't just make wee and excrete waste. They have many functions including secreting hormones that help control blood pressure and red blood cell formation. The heart and circulatory system is another example of vascular damage, but on bigger vessels (macro vascular) a breakdown in blood supply to cardiac muscle = heart attacks. The poor blood supply damages nerves, which still need a healthy blood supply. This most commonly effect peripheral (distant) nerves, which is why you get numbness and tingling and loss of sensation. Why do diabetic people get feet amputated? Well they have a loss of sensation so they don't realise when they injure the soles of their feet, such as if they step on something. And injuries need a good blood supply to heal properly, so guess what? The injury doesn't heal, an ulcer forms and eventually so much damage is done that it's irrepairable and needs amputating. There's also a condition called Charcot's joint which is a chronic breakdown of joints around the ankle/foot, again caused by a lack of sensation. The nerve problems don't end their. A lot of the body is controlled by autonomic nerves, that sense what's going on and adjust things automatically. If they break down because of diabetic neuropathy, the natural balance of hormones and control over body systems can be thrown into chaos, the effects of this are wide ranging and difficult to control. It's also the way that organs 'sense' so those heart attacks diabetics can be prone to can be missed because the heart can't give the usual signs out that it's in trouble (such as the classic crushing chest pain). It's also a hypercoaguable condition due to high blood sugar, vessel damage and inflammation. So you are more likely to have strokes and clots. Type 2 diabetes is also almost always associated with obesity, so throw in the extra health problems caused by obesity. This is just a few examples, diabetes really is a systemic condition that can affect pretty much anywhere. Sadly, in most cases of type 2 diabetes it was probably preventable. Edit: as for a specific reason why blood vessels are damaged, I don't think it is 100% understood but 2 mechanisms have been identified. Firstly, high levels of sugars and fats promote oxidative stress which directly damages blood vessels and other cells. Secondly, the effect of the high blood sugar interferes with an enzyme that produces nitric oxide within blood vessels. Nitric oxide acts as a vasodilator, so the blood vessels stay constricted, pressure within them rises and damage takes place that way as well. It's probably another reason diabetes is linked to high blood pressure and why it's so important (and beneficial) to keep blood pressure controlled in diabetics.
passages: Section::::Signs and symptoms.:Complications.
  
  All forms of diabetes increase the risk of long-term complications. These typically develop after many years (10–20) but may be the first symptom in those who have otherwise not received a diagnosis before that time.
  
  The major long-term complications relate to damage to blood vessels. Diabetes doubles the risk of cardiovascular disease and about 75% of deaths in people with diabetes are due to coronary artery disease. Other macrovascular diseases include stroke, and peripheral artery disease.
   Overall, complications are far less common and less severe in people with well-controlled blood sugar levels. However, (non-modifiable) risk factors such as age at diabetes onset, type of diabetes, gender and genetics play a role. Some genes appear to provide protection against diabetic complications, as seen in a subset of long-term diabetes type 1 survivors without complications.
  
  Section::::Statistics.
  
  As of 2010, there were about 675,000 diabetes-related emergency department (ED) visits in the U.S. which involved neurological complications, 409,000 ED visits with kidney complications, and 186,000 ED visits with eye complications.
  
  Section::::Acute.
  
  Section::::Acute.:Diabetic ketoacidosis.
   Chronic complications occur due to a mix of microangiopathy, macrovascular disease and immune dysfunction in the form of autoimmune disease or poor immune response, most of which are difficult to manage. Microangiopathy can affect all vital organs, kidneys, heart and brain, as well as eyes, nerves, lungs and locally gums and feet. Macrovascular problems can lead to cardiovascular disease including erectile dysfunction. Female infertility may be due to endocrine dysfunction with impaired signalling on a molecular level.
   The following is a comprehensive list of other causes of diabetes:
  
  BULLET::::- Genetic defects of β-cell function
  
  BULLET::::- Maturity onset diabetes of the young
  
  BULLET::::- Mitochondrial DNA mutations
  
  BULLET::::- Genetic defects in insulin processing or insulin action
  
  BULLET::::- Defects in proinsulin conversion
  
  BULLET::::- Insulin gene mutations
  
  BULLET::::- Insulin receptor mutations
  
  BULLET::::- Exocrine pancreatic defects
  
  BULLET::::- Chronic pancreatitis
  
  BULLET::::- Pancreatectomy
  
  BULLET::::- Pancreatic neoplasia
  
  BULLET::::- Cystic fibrosis
  
  BULLET::::- Hemochromatosis
  
  BULLET::::- Fibrocalculous pancreatopathy
  
  BULLET::::- Endocrinopathies
  
  BULLET::::- Growth hormone excess (acromegaly)
  
  BULLET::::- Cushing syndrome
  
  BULLET::::- Hyperthyroidism
  
  BULLET::::- Hypothyroidism
  
  BULLET::::- Pheochromocytoma
  
  BULLET::::- Glucagonoma
  
  BULLET::::- Infections
  
  BULLET::::- Cytomegalovirus infection
  
  BULLET::::- Coxsackievirus B
  
  BULLET::::- Drugs
  
  BULLET::::- Glucocorticoids
   BULLET::::- "Folic acid:"
   Diabetes mellitus type 1 is a chronic autoimmune disorder in which the immune system attacks the insulin-secreting cells of the pancreas. Insulin is needed to keep blood sugar levels within optimal ranges, and its lack can lead to high blood sugar. As an untreated chronic condition, diabetic neuropathy can result. In addition, if there is not enough insulin for glucose to be used within cells, the medical emergency diabetic ketoacidosis, which is often the first symptom that a person with type 1 diabetes may have, can result. Type 1 diabetes can develop at any age but is most often diagnosed before adulthood. For people living with type 1 diabetes, insulin injections are critical for survival.
   A number of approaches have been explored to understand causes and provide treatments for type 1.
  
  Section::::Research.:Diet.
   BULLET::::- "Respiratory infections" such as pneumonia and influenza are more common among individuals with diabetes. Lung function is altered by vascular disease and inflammation, which leads to an increase in susceptibility to respiratory agents. Several studies also show diabetes associated with a worse disease course and slower recovery from respiratory infections.
   BULLET::::- Recurring gum or skin infections
  
  BULLET::::- Recurring vaginal or bladder infections
  
  BULLET::::- Acetone odor during diabetic ketoacidosis (DKA)
  
  Section::::Causes of diabetes.
  
  Section::::Causes of diabetes.:Causes of diabetes mellitus type 1.
  
  BULLET::::- Genetic causes of diabetes mellitus type 1
  
  Section::::Causes of diabetes.:Causes of diabetes mellitus type 2.
  
  BULLET::::- Genetic causes of diabetes mellitus type 2
  
  BULLET::::- Lifestyle causes of diabetes mellitus type 2
  
  Section::::Related conditions.
  
  BULLET::::- Impaired glucose tolerance –
  
  Section::::Preventing diabetes.
  
  Section::::Preventing diabetes.:Preventing diabetes mellitus type 1.
  
  Currently, there is no known way to prevent diabetes mellitus type 1.
  
  Section::::Preventing diabetes.:Preventing diabetes mellitus type 2.
   Dietary factors also influence the risk of developing type 2 diabetes. Consumption of sugar-sweetened drinks in excess is associated with an increased risk. The type of fats in the diet are important, with saturated fats and trans fatty acids increasing the risk, and polyunsaturated and monounsaturated fat decreasing the risk. Eating a lot of white rice appears to play a role in increasing risk. A lack of exercise is believed to cause 7% of cases. Persistent organic pollutants may play a role.
  
  Section::::Cause.:Genetics.
   BULLET::::- "Female infertility" is more common in women with diabetes type 1, despite modern treatment, also delayed puberty and menarche, menstrual irregularities (especially oligomenorrhoea), mild hyperandrogenism, polycystic ovarian syndrome, fewer live born children and possibly earlier menopause. Animal models indicate that on the molecular level diabetes causes defective leptin, insulin and kisspeptin signalling.
  
  Section::::Chronic.:Abnormal immune responses.
  
  The immune response is impaired in individuals with diabetes mellitus. Cellular studies have shown that hyperglycemia both reduces the function of immune cells and increases inflammation.
   Research from 2007 suggested that in type 1 diabetics, the continuing autoimmune disease which initially destroyed the beta cells of the pancreas may also cause neuropathy, and nephropathy. 
  
  In 2008 it was even suggested to treat retinopathy with drugs to suppress the abnormal immune response rather than by blood sugar control.
  
  Section::::Risk factors.:Genetic factors.
  
  The known familial clustering of the type and degree of diabetic complications indicates, that genetics play a role in causing complications:
  
  BULLET::::- the 2001 observation, that non-diabetic offspring of type 2 diabetics had increased arterial stiffness and neuropathy despite normal blood glucose levels,
   BULLET::::- it is likely that there is genetic susceptibility to develop Type 2 diabetes under certain environmental conditions
  
  BULLET::::- Other types of impaired glucose tolerance (see the Diabetes)
  
  BULLET::::- Insulinoma – a tumor of beta cells producing excess insulin or reactive hypoglycemia.
   Dietary factors also influence the risk of developing type 2 diabetes. Consumption of sugar-sweetened drinks in excess is associated with an increased risk. The type of fats in the diet is also important, with saturated fat and trans fats increasing the risk and polyunsaturated and monounsaturated fat decreasing the risk. Eating lots of white rice, and other starches, also may increase the risk of diabetes. A lack of physical activity is believed to cause 7% of cases.
  
  Section::::Causes.:Gestational diabetes.
   Section::::Acute.:Hypoglycemia.
   Chronic elevation of blood glucose level leads to damage of blood vessels called angiopathy. The endothelial cells lining the blood vessels take in more glucose than normal, since they do not depend on insulin. They then form more surface glycoproteins than normal, and cause the basement membrane to grow thicker and weaker. The resulting problems are grouped under "microvascular disease" due to damage to small blood vessels and "macrovascular disease" due to damage to the arteries.
   There is on the order of a 10-fold difference in occurrence among Caucasians living in different areas of Europe, and people tend to acquire the disease at the rate of their particular country. Environmental triggers and protective factors under research include dietary agents such as proteins in gluten, time of weaning, gut microbiota, viral infections, and bacterial infections like paratuberculosis.
  
  Section::::Cause.:Environmental.:Chemicals and drugs.
   Patient education and compliance with treatment is very important in managing the disease. Improper use of medications and insulin can be very dangerous causing hypo- or hyper-glycemic episodes.
  
  Section::::Lifestyle modification.:Insulin.
  
  For type 1 diabetics, there will always be a need for insulin injections throughout their life, as the pancreatic beta cells of a type 1 diabetic are not capable of producing sufficient insulin. However, both type 1 and type 2 diabetics can see dramatic improvements in blood sugars through modifying their diet, and some type 2 diabetics can fully control the disease by dietary modification.
   Diabetes mellitus is a chronic disease, for which there is no known cure except in very specific situations. Management concentrates on keeping blood sugar levels as close to normal, without causing low blood sugar. This can usually be accomplished with a healthy diet, exercise, weight loss, and use of appropriate medications (insulin in the case of type 1 diabetes; oral medications, as well as possibly insulin, in type 2 diabetes).
   The degree of insulin deficiency is variable. Diabetes can develop from infancy through middle adult life, and some family members who carry the gene remain free of diabetes into later adult life. Most of those who develop diabetes show atrophy of the entire pancreas, with mild or subclincal deficiency of exocrine as well as endocrine function.
   Type 2 Diabetes Mellitus is a chronic condition which is largely preventable and manageable but difficult to cure. Management concentrates on keeping blood sugar levels as close to normal ("euglycemia") as possible without presenting undue patient danger. This can usually be with close dietary management, exercise, and use of appropriate medications (insulin only in the case of type 1 diabetes mellitus. Oral medications may be used in the case of type 2 diabetes, as well as insulin).
   Section::::North America and the Caribbean.
  
  Current IDF data proposes more than 38.4 million people in North American and the Caribbean have diabetes and projects this number will increase to 51.2 million by 2030. In 2012, 11% of (or approximately 4.2 million) adults in the NAC Region endured the disease; this year, diabetes was responsible for 287,020 deaths in North America.
   Section::::Signs and symptoms.
  
  MODY is the final diagnosis in 1%–2% of people initially diagnosed with diabetes. The prevalence is 70–110 per million people. 50% of first-degree relatives will inherit the same mutation, giving them a greater than 95% lifetime risk of developing MODY themselves. For this reason, correct diagnosis of this condition is important. Typically patients present with a strong family history of diabetes (any type) and the onset of symptoms is in the second to fifth decade.
  
  There are two general types of clinical presentation.
   BULLET::::- the 2008 observation, that non-diabetic first-degree relatives of diabetics had elevated enzyme levels associated with diabetic renal disease and nephropathy.
  
  BULLET::::- the 2007 finding that non-diabetic family members of type 1 diabetics had increased risk for microvascular complications,
  
  BULLET::::- such as diabetic retinopathy
  
  Section::::Risk factors.:Mechanisms.
   BULLET::::- "Diabetic retinopathy", growth of friable and poor-quality new blood vessels in the retina as well as macular edema (swelling of the macula), which can lead to severe vision loss or blindness. Retinopathy is the most common cause of blindness among non-elderly adults in the developed world.
  
  BULLET::::- "Diabetic encephalopathy" is the increased cognitive decline and risk of dementia, including (but not limited to) the Alzheimer's type, observed in diabetes. Various mechanisms are proposed, like alterations to the vascular supply of the brain and the interaction of insulin with the brain itself.
  