Fasting plasma glucose level: If your blood glucose level is 7.0 mmol/L or higher after having not eaten anything for at least 8 hours – called fasting – your doctor may diagnose diabetes. If your blood glucose level is between 6.1 to 6.9 mmol/L, your doctor may diagnose impaired fasting glucose or prediabetes (a condition that may later develop into diabetes).
But preventing the disease from progressing if you already have it requires first being able to spot the signs and symptoms of diabetes when they appear. While some type 2 diabetes symptoms may not ever show up, you can watch out for the following common signs of the disease and alert your doctor, especially if you have any of the common risk factors for diabetes. Also keep in mind that while most signs of type 2 diabetes are the same in men and women, there are some distinctions.
Sources of processed or added sugar, including condiments, honey, and especially sugary drinks, are just a few of the potential culprits for weight gain, Grieger says, and it’s when they’re consumed in excess that they can contribute to diabetes risk. “The largest source of added sugar comes from sweetened beverages. They run the gamut of soda, sweetened tea, juices with added sugar, sports drinks — it’s a plethora. Just about everything we drink has added sugar in it, except for water,” she explains.
Another area of pathologic changes associated with diabetes mellitus is the nervous system (diabetic neuropathy), particularly in the peripheral nerves of the lower extremities. The patient typically experiences a “stocking-type” anesthesia beginning about 10 years after the onset of the disease. There may eventually be almost total anesthesia of the affected part with the potential for serious injury to the part without the patient being aware of it. In contrast, some patients experience debilitating pain and hyperesthesia, with loss of deep tendon reflexes.
Keeping track of the number of calories provided by different foods can become complicated, so patients usually are advised to consult a nutritionist or dietitian. An individualized, easy to manage diet plan can be set up for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food exchange lists. Each food exchange contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will consist of a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at meal times and as snacks. Patients have flexibility in choosing which foods they eat as long as they stick with the number of exchanges prescribed.
With such a surplus of food nowadays, it's easy to overindulge without physical activity, leading to weight gain and, for some people, eventual Type 2 diabetes. "It's a lack of exercise and still eating like you're 20 years old," says Susan M. De Abate, a nurse and certified diabetes educator and team coordinator of the diabetes education program at Sentara Virginia Beach General Hospital.
No single environmental trigger has been identified as causing diabetes mellitus, however both infectious agents and dietary factors are thought to be important. Various viruses have been implicated in the development of type I DM. They may act by initiating or modifying the autoimmune process. In particular, the rubella virus and coxsackie viruses have been closely studied. In particular, congenital rubella infection has shown direct relationships with the development of type 1 diabetes mellitus. This is presumably due to the virus (or antibodies against it) damaging the beta cells of the pancreas. Some research has looked at dietary factors that may be associated with type 1 diabetes. In particular, cow’s milk proteins (such as bovine serum albumin) which may have some similarities to pancreatic islet cell markers may be able to trigger the autoimmune process. Other chemicals including nitrosamines have been identified as causes of diabetes mellitus in animal models, but not in humans.

Diagnosis. The most common diagnostic tests for diabetes are chemical analyses of the blood such as the fasting plasma glucose. Capillary blood glucose monitoring can be used for screening large segments of the population. Portable equipment is available and only one drop of blood from the fingertip or earlobe is necessary. Capillary blood glucose levels have largely replaced analysis of the urine for glucose. Testing for urinary glucose can be problematic as the patient may have a high renal threshold, which would lead to a negative reading for urinary glucose when in fact the blood glucose level was high.

All types of diabetes mellitus have something in common. Normally, your body breaks down the sugars and carbohydrates you eat into a special sugar called glucose. Glucose fuels the cells in your body. But the cells need insulin, a hormone, in your bloodstream in order to take in the glucose and use it for energy. With diabetes mellitus, either your body doesn't make enough insulin, it can't use the insulin it does produce, or a combination of both.
There are two major types of diabetes, called type 1 and type 2. Type 1 diabetes was also formerly called insulin dependent diabetes mellitus (IDDM), or juvenile-onset diabetes mellitus. In type 1 diabetes, the pancreas undergoes an autoimmune attack by the body itself, and is rendered incapable of making insulin. Abnormal antibodies have been found in the majority of patients with type 1 diabetes. Antibodies are proteins in the blood that are part of the body's immune system. The patient with type 1 diabetes must rely on insulin medication for survival.
^ Jump up to: a b c d GBD 2015 Disease and Injury Incidence and Prevalence, Collaborators. (8 October 2016). "Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015". The Lancet. 388 (10053): 1545–1602. doi:10.1016/S0140-6736(16)31678-6. PMC 5055577. PMID 27733282.
To understand why insulin is important, it helps to know more about how the body uses food for energy. Your body is made up of millions of cells. To make energy, these cells need food in a very simple form. When you eat or drink, much of the food is broken down into a simple sugar called "glucose." Then, glucose is transported through the bloodstream to these cells where it can be used to provide the energy the body needs for daily activities.

The levels of glucose in the blood vary normally throughout the day. They rise after a meal and return to pre-meal levels within about 2 hours after eating. Once the levels of glucose in the blood return to premeal levels, insulin production decreases. The variation in blood glucose levels is usually within a narrow range, about 70 to 110 milligrams per deciliter (mg/dL) of blood in healthy people. If people eat a large amount of carbohydrates, the levels may increase more. People older than 65 years tend to have slightly higher levels, especially after eating.

Weight loss surgery in those who are obese is an effective measure to treat diabetes.[101] Many are able to maintain normal blood sugar levels with little or no medication following surgery[102] and long-term mortality is decreased.[103] There however is some short-term mortality risk of less than 1% from the surgery.[104] The body mass index cutoffs for when surgery is appropriate are not yet clear.[103] It is recommended that this option be considered in those who are unable to get both their weight and blood sugar under control.[105][106]
Examples of simple or refined carbohydrates, on the other hand, exist in various forms — from the sucrose in the table sugar you use to bake cookies, to the various kinds of added sugar in packaged snacks, fruit drinks, soda, and cereal. Simple carbohydrates are natural components of many fresh foods, too, such as the lactose in milk and the fructose in fruits, and therefore, a healthy, well-balanced diet will always contain these types of sugars.
Insulin is only recommended for individuals for type 2 diabetics when they have not been able to get blood sugars low enough to prevent complications through other means. To avoid insulin, those with this health condition should work very hard to follow a healthy eating plan that includes a lot of vegetables and lean proteins, exercise every day, and keep stress in perspective. They also should take their oral drugs regularly. It can be difficult to follow these recommendations and the help of your doctor, nutritionist, diabetes educator, health coach, or integrative medicine practitioner may be helpful. If you who want to avoid taking medicine, work with health professionals who are knowledgeable about lifestyle medicine, and can help you understand how to fit the changes into your life.
When the glucose concentration in the blood remains high over time, the kidneys will reach a threshold of reabsorption, and glucose will be excreted in the urine (glycosuria).[62] This increases the osmotic pressure of the urine and inhibits reabsorption of water by the kidney, resulting in increased urine production (polyuria) and increased fluid loss. Lost blood volume will be replaced osmotically from water held in body cells and other body compartments, causing dehydration and increased thirst (polydipsia).[60]

Type 1 diabetes occurs when your immune system, the body’s system for fighting infection, attacks and destroys the insulin-producing beta cells of the pancreas. Scientists think type 1 diabetes is caused by genes and environmental factors, such as viruses, that might trigger the disease. Studies such as TrialNet are working to pinpoint causes of type 1 diabetes and possible ways to prevent or slow the disease.
Type 2 diabetes which accounts for 85-95 per cent of all diabetes has a latent, asymptomatic period of sub-clinical stages which often remains undiagnosed for several years1. As a result, in many patients the vascular complications are already present at the time of diagnosis of diabetes, which is often detected by an opportunistic testing. Asian populations in general, particularly Asian Indians have a high risk of developing diabetes at a younger age when compared with the western populations5. Therefore, it is essential that efforts are made to diagnose diabetes early so that the long term sufferings by the patients and the societal burden can be considerably mitigated.
Commonly, diabetic patients’ random blood glucose measurement will be greater than 200 mg/dL. Additionally, diabetic patients’ urinalysis will be positive for greater than 30 mg/g of microalbumin on at least two of three consecutive sampling dates. Type 2 diabetics who have had diabetes mellitus for more than 2 years will usually have a fasting C-peptide level greater than 1.0 ng/dL. Patients with type 1 diabetes will have islet cell and anti-insulin autoantibodies present in their blood within 6 months of diagnosis. These antibodies, though, usually fade after 6 months.
There is no single gene that “causes” type 1 diabetes. Instead, there are a large number of inherited factors that may increase an individual’s likelihood of developing diabetes. This is known as multifactorial inheritance. The genes implicated in the development of type 1 diabetes mellitus control the human leukocyte antigen (HLA) system. This system is involved in the complex process of identifying cells which are a normal part of the body, and distinguishing them from foreign cells, such as those of bacteria or viruses. In an autoimmune disease such as diabetes mellitus, this system makes a mistake in identifying the normal ‘self’ cells as ‘foreign’, and attacks the body.  
Metformin (Glucophage, Glucophage XR, Glumetza, Fortamet, Riomet) belongs to a class of drugs called biguanides. Metformin is first-line therapy for most type 2 diabetics. It works to stop the liver from making excess glucose, and has a low risk of hypoglycemia. Hypoglycemia, or very low blood sugar can cause symptoms such as sweating, nervousness, heart palpitations, weakness, intense hunger, trembling, and problems speaking. Many patients lose some weight taking metformin, which is also helpful for blood sugar control.
Since cardiovascular disease is a serious complication associated with diabetes, some have recommended blood pressure levels below 130/80 mmHg.[89] However, evidence supports less than or equal to somewhere between 140/90 mmHg to 160/100 mmHg; the only additional benefit found for blood pressure targets beneath this range was an isolated decrease in stroke risk, and this was accompanied by an increased risk of other serious adverse events.[90][91] A 2016 review found potential harm to treating lower than 140 mmHg.[92] Among medications that lower blood pressure, angiotensin converting enzyme inhibitors (ACEIs) improve outcomes in those with DM while the similar medications angiotensin receptor blockers (ARBs) do not.[93] Aspirin is also recommended for people with cardiovascular problems, however routine use of aspirin has not been found to improve outcomes in uncomplicated diabetes.[94]
Type 2 diabetes was also previously referred to as non-insulin dependent diabetes mellitus (NIDDM), or adult-onset diabetes mellitus (AODM). In type 2 diabetes, patients can still produce insulin, but do so relatively inadequately for their body's needs, particularly in the face of insulin resistance as discussed above. In many cases this actually means the pancreas produces larger than normal quantities of insulin. A major feature of type 2 diabetes is a lack of sensitivity to insulin by the cells of the body (particularly fat and muscle cells).
High blood glucose sets up a domino effect of sorts within your body. High blood sugar leads to increased production of urine and the need to urinate more often. Frequent urination causes you to lose a lot of fluid and become dehydrated. Consequently, you develop a dry mouth and feel thirsty more often. If you notice that you are drinking more than usual, or that your mouth often feels dry and you feel thirsty more often, these could be signs of type 2 diabetes.