Impaired fasting glucose

Impaired fasting glucose (IFG) is a type of prediabetes, in which the blood sugar level during fasting is consistently higher than what are considered normal levels; however, the level is not high enough to be diagnosed as diabetes mellitus.^[1] This pre-diabetic state is associated with insulin resistance and increased risk of cardiovascular pathology, although of lesser risk than impaired glucose tolerance (IGT). IFG can progress to type 2 diabetes mellitus if lifestyle changes are not made. There is a 50% risk over 10 years of progressing to overt diabetes. A recent study cited the average time for progression as less than three years.^[2]

Fasting blood glucose levels are in a continuum within a given population, with higher fasting glucose levels corresponding to a higher risk for complications caused by the high glucose levels. Impaired fasting glucose is defined as a fasting glucose that is higher than the upper limit of normal, but not high enough to be classified as diabetes mellitus. Some patients with impaired fasting glucose can also be diagnosed with impaired glucose tolerance, but many have normal responses to a glucose tolerance test.

Signs and Symptoms

The World Health Organization (WHO) criteria for impaired fasting glucose differ from the American Diabetes Association (ADA) criteria, because the normal range of glucose is defined differently. The WHO has defined the upper limit of normal at under 110 mg/dL (plasma). However, fasting glucose levels 100 mg/dL (plasma) and higher have been shown to increase complication rates significantly , and the ADA has lowered the upper limit of normal accordingly, to a fasting glucose under 100 mg/dL (plasma).

• WHO criteria: fasting plasma glucose level from 6.1 mmol/l (110 mg/dL) to 6.9 mmol/l (125 mg/dL).^[3][4][5]
• ADA criteria: fasting plasma glucose level from 5.6 mmol/L (100 mg/dL) to 6.9 mmol/L (125 mg/dL).

Sudden sweating, confusion, thirst, hunger, heart palpitations, impaired speech, difficulty focusing - these are just a few symptoms and are not just limited to these.

Risk factors

IFG is a risk factor for mortality due to the serious complications of type 2 diabetes mellitus.^[6] Diabetes is a multi-factor disease and it can affect many areas of the body. The depositions of plaque in the arteries known as atherosclerosis are a potential risk that is elevated in diabetic individuals. This may lead to heart attack or stroke. Blindness is another concern associated with type 2 diabetes. It is caused by microvascular disease in which high blood glucose levels damage blood vessels in the retina by the formation of scar tissue or hemorrhage. Not only do these high levels cause vision loss, they may also cause sensory nerve damage (neuropathy). This presents as tingling, numbness or pain and in the most severe cases requires amputation. When these elevated levels of blood glucose are chronic there is a potential that irreversible kidney damage can occur. It is important that individuals with IFG or diabetes mellitus monitor their condition and make healthy lifestyle choices to reduce the onset of these life-threatening symptoms. Pre-diabetic individuals who have abdominal obesity, high blood pressure, high LDL cholesterol, low HDL cholesterol, and high levels of triglycerides in the blood have an increased risk of developing type 2 diabetes mellitus. These risk factors are known collectively as the metabolic syndrome.^[1] Recent evidence suggests that, similar to diabetes mellitus, individuals with IFG have higher degree of periodontal inflammation.^[7]

Prevention

With proper education, eating habits, physical activity, weight management, and lifestyle the risk of developing type 2 diabetes mellitus is reduced.^[8] Blood glucose levels can be managed by the healthy eating and physical activity guidelines as an individual with normal blood glucose levels, however some minor modifications may be required. These variations depend on the individual, but it may include a decrease in the amount of carbohydrates consumed. The consumption of alcohol should also be limited, but moderate drinking may be protective. Advice and guidelines about eating a nutritious, balanced meal can be found using Canada's Food Guide. Vegetables and fruit should be consumed in the largest proportions. Regular physical activity has the potential to reduce insulin resistance and help decrease elevated blood glucose levels.^[9]

See also

• Diabetic diet
• Glucose tolerance test
• Impaired glucose tolerance
• Low GI diet

References