6 Signs of Prediabetes and Blood Test Results

With an estimated 1 in 3 Americans over the age of 20 years suffering with prediabetes, it is important to diagnose and treat this condition as early as possible. Prediabetes is reversible but if left untreated, it will eventually lead to diabetes which cannot be reversed. Diabetes is the seventh leading cause of death in the United States and to a large extent it can be prevented, particularly if it is attended to in the prediabetes stage or even before prediabetes arises.

Read more on how to cure prediabetes.

About Prediabetes

Prediabetes is a condition where the body does not respond as normal to insulin. Since insulin is responsible for lowering blood glucose levels, in prediabetes the glucose levels are elevated but not as high as in diabetes. Prediabetes is also known as glucose intolerance or impaired glucose tolerance. There is sufficient insulin in the bloodstream and sometimes even high levels of insulin but the blood glucose levels do not decrease as normal.

In type 1 diabetes mellitus there is a lack of insulin being produced by and secreted from the pancreas. This is the less common type of diabetes. In the more common form of diabetes, also known as type 2 diabetes, the body becomes unresponsive to insulin. Prediabetes, as its name suggests, precedes the onset of ‘full blown’ type 2 diabetes. It is essentially the early stage of the body becoming unresponsive to insulin.

Why does prediabetes occur?

The exact cause of prediabetes is unclear but it is associated with the same risk factors as type 2 diabetes. While genetic factors and a family history of type 2 diabetes are strong risk factors for developing prediabetes and possibly type 2 diabetes later, there are other factors that also play a role. Being overweight or obese and living a sedentary lifestyle are other risk factors as well as dietary habits and sleep patterns.

Although the exact cause is not known, the mechanism behind prediabetes and type 2 diabetes is well understood. In prediabetes the body becomes less responsive to insulin. This is known as insulin resistance. It does not mean that the body is completely unresponsive to insulin.

The pancreas tries to accommodate by increasing insulin levels in the bloodstream to achieve the same effect of lowering blood glucose levels, although not as effectively. Eventually the insulin secretion decreases although the insulin resistance continues. It is at this point that type 2 diabetes develops.

Read more on signs of insulin resistance.

How to Spot Prediabetes

Most of the time prediabetes does not present with any signs or symptoms. A person can have prediabetes for long periods of time and not be aware without diagnostic testing. The preferred method for diagnosing prediabetes is the oral glucose tolerance test (OGTT) although A1c (also known as HbA1c) is another method that could be used. These tests should be conducted routinely on people who are at high risk of developing diabetes.

In an oral glucose tolerance test, a glucose solution is administered to a person. Blood samples are taken before and after administering the glucose solution and the blood glucose levels in these samples are tested. An A1c also requires a blood sample and measures the glucose levels in red blood cells which are an indication of the average blood glucose levels in preceding months.

Dark Skin Patches

Darkening of the skin on the folds of the body, like the neck, armpits and knuckles, may be an indicator of impaired glucose intolerance. This is known as acanthosis nigricans and can arise due to other causes. It does not affect every person with prediabetes. Therefore this darkening of the skin is not considered to be a reliable indicator of prediabetes. There is no itching or other symptoms at the affected part of the skin except for the darkening.

Increased Urination

Frequent urination is a common symptom of diabetes due to the larger volume urine output (polyuria). However, it is not usually seen in prediabetes. In fact diabetes would usually have developed by the time increased urination becomes obvious. Nevertheless persistently raised blood glucose levels will alter urine and impair the reabsorption of water in the kidneys. This will result in increased urination.

Increased Thirst

Another characteristic feature of diabetes is increased thirst (polydipsia). The loss of water through increased urination will cause a proportional increase in thirst as the body requires more water to prevent or counteract dehydration. As with increased urination, this is not usually seen in prediabetes. However, it can occur if there is water loss with increased urination as a result of persistently raised blood glucose levels.


Fatigue is a common non-specific sign of diabetes. It is also present to a milder extent in prediabetes. Fatigue occurs for several reasons. With the body’s cells being unable to respond to insulin and take in sufficient glucose from the bloodstream, energy production may be lower than normal. Furthermore, fatigue may also be due in part to dehydration. Lastly, people who are overweight or obese and live a sedentary lifestyle are more likely to feel fatigued, even without diabetes or prediabetes being present.

Unintentional Weight Loss

Weight loss that is not purposeful and does not correlate with eating habits is another sign of diabetes. It may sometimes be evident in prediabetes. However, since many people with prediabetes may be overweight or obese, they may not notice this weight loss. Despite eating as normal (even if excessive), diabetes results in breakdown of fat within the body that leads to unintentional weight loss.

Blood Test Results

The most conclusive sign of prediabetes is higher than normal readings for tests like the oral glucose tolerance test (OGTT) or A1c (HbA1C) test.

  • Oral glucose tolerance test
    – Prediabetes = 140 mg/DL to 199 mg/DL (7.8 mmol/dL to 11 mmol/L)
    – Diabetes = 200 mg/DL (11.1 mmol/L) and higher
  • A1C blood test
    – Prediabetes = 5.7 to 6.4%
    – Diabetes = 6.5% or higher

A fasting blood glucose test can also be done to detect prediabetes or diabetes. This involves not eating or drinking anything for at least 8 hours and then measuring the blood glucose levels. Even if a fasting blood glucose level does indicate an abnormality, prediabetes should only be diagnosed after conducting a follow up oral glucose tolerance test or A1C test.

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