Type 2 diabetes is a complicated condition. Its precise causes remain elusive to this day, and researchers are still hard at work trying to better understand why some individuals are prone to its development. However, it seems clear that this condition does not simply arise out of nowhere. Rather, it seems to develop slowly over time, often being preceded by subtle metabolic changes which gradually grow in significance.

One of the earliest precursors to a potential occurrence of type 2 diabetes is the development of insulin resistance (IR). This condition, characterized by abnormal cellular metabolism of glucose, can be a clear warning sign of more harmful changes to come. Fortunately, the condition is readily detectable, and early interventions can often control the progression to more worrying diagnoses.

What is insulin resistance?

Insulin resistance describes an impaired ability of the body’s cells to import glucose from the bloodstream in response to the presence of insulin. Normally, insulin is used as a chemical messenger that co-ordinates the digestion of glucose and regulates blood sugar levels throughout the day. However, this process can be disrupted by a variety of factors that cause the body to become de-sensitized to insulin’s presence. Like with caffeine or alcohol, as insulin is released more frequently and in greater amounts, the body begins to develop a tolerance to it and no longer responds as effectively as it should.

Ultimately, insulin resistance can progress to the point where a person is diagnosed as having type 2 diabetes. Although the two conditions are closely related in many ways, type 2 diabetes and insulin resistance are wholly distinct conditions. IR often precipitates pre-diabetes and type 2 diabetes, but it can also be present in non-diabetic individuals who will never end up developing pre-diabetes or diabetes.

With that said, it can be useful to think of type 2 diabetes as an advanced stage in the progression of insulin resistance. The distinguishing characteristic in the progression from insulin resistance to type 2 diabetes is perhaps that the body of a type 2 diabetic is no longer able to roughly compensate for the degree of insulin resistance by secreting excess insulin or making do with less-than-optimal blood sugar regulation.

How does insulin resistance develop?

The analogy to alcohol or caffeine tolerance is helpful, but the reality of insulin resistance is more complex than simple over-exposure to insulin. Research into the exact factors that contribute to IR development is still ongoing, but current science seems to indicate a mixture of genetic and lifestyle-related factors. While any one factor may increase the likelihood that a person will develop IR, no one factor can be conclusively defined as the cause of IR.

Some researchers have indicated that there may be a hereditary element to IR. This means that having one or more family members with IR can statistically suggest a higher likelihood of developing the condition. Still, it could be that other factors must be present to trigger the development of IR even for those who are genetically predisposed. Lifestyle factors likely have the potential to be such triggers. Sedentary lifestyle, poor diet, and excess body fat have all been reported as possible contributors to the development or progression of IR.

The importance of detecting insulin resistance

As mentioned, IR is a relatively malleable condition. By that, we mean that patients often have a good degree of control over how severely its symptoms manifest, and how quickly it progresses (if it progresses at all). Additionally, IR tends to be clustered with other metabolic and health-related co-morbidities and can therefore be a signal to doctors to investigate other aspects of a patient’s health. While this all sounds optimistic, there’s a catch: patients can’t control their IR if they are unaware of its existence. Detecting IR is therefore a necessary first step in treating it effectively.

Being a progressive condition, time is of the essence when it comes to IR treatment. Early detection gives patients and their practitioners time to work together to construct an effective strategy for the mitigation of future harm. The longer IR goes untreated, the more likely it is that a patient will begin to suffer its harmful effects, such as damage to the cardiovascular and nervous systems of the body. Remember, as the saying goes, “An ounce of prevention is worth a pound of cure.”

Symptoms, warning signs, and risk factors

Insulin resistance detection often begins with patients noticing unusual symptoms that might suggest insulin resistance. Patients who have one or more risk factors for IR should be especially vigilant for these symptoms, as they are at a greater statistical likelihood for developing the condition. Please note that it is crucial for patients not to attempt a self-diagnosis of insulin resistance(or any other condition) based on perceived symptoms. If you are experiencing troubling or unusual symptoms of any kind, please consult with a doctor for a formal diagnosis.

Risk factors for insulin resistance can include:

  • Obesity or excess body weight;
  • High blood pressure;
  • Family history of diabetes or insulin resistance;
  • Sedentary lifestyle;
  • High cholesterol;
  • Being prescribed certain medications, like beta-blockers or glucocorticoids.

Symptoms of insulin resistance may include:

  • Increased thirst or urination frequency;
  • Blurred vision;
  • Dark patches of skin around the neck;
  • Wounds that heal slowly;
  • A tingling or numb sensation in the extremities;
  • Other symptoms – everyone is unique, and your symptoms of IR may not match those on this list.

Detecting and diagnosing insulin resistance

Patients who believe they may be at risk of insulin resistance based on symptoms or risk factors should consider seeing their doctor for a professional evaluation. The doctor will likely conduct a basic physical and verbal assessment of the patient, wherein they will consider the patient’s medical and family history, as well as any symptoms the patient is displaying. They will likely also conduct one or several basic tests that can provide them with numerical data about biological markers of insulin resistance. We describe some of the more common tests below.

Hgba1c

A common test used for diagnosing IR and monitoring type 2 diabetes alike involves measuring HbA1c levels. HbA1c is the medical term for glycated hemoglobin, which, in layperson’s terms, describes the proportion of hemoglobin molecules (a core structure of red blood cells) with glucose affixed to them.

HbA1c levels are useful because they tend to correlate to a person’s average blood sugar levels over a period of several months. While not perfect, this test can therefore serve as a rough proxy for how high or low a person’s blood sugar levels have been for a period of time. Since individuals with insulin resistance tend to have higher blood sugar levels due to a dysfunctional capacity for glucose metabolism, elevated HbA1c levels are generally consistent with a finding that a person has some degree of insulin resistance. The test is not perfectly reliable, though, as a number of other factors can influence the results.

There are no special preparations a patient must undergo prior to an HbA1c test. They will simply have a blood sample taken by their doctor, which will be sent to a lab for analysis. The results will be interpreted by the doctor, who will make some determination based on where the levels fall relative to what is expected for a healthy individual. Levels above 5.7% are typically considered abnormal, but patients should defer to their doctor’s analysis to best understand their test results.

Fasting insulin

Another blood test that your doctor may perform is a test of your fasting insulin levels. This test takes advantage of the different ways in which IR and non-IR individuals respond to the presence of insulin as a means of metabolizing food.

In healthy individuals, insulin rises following a meal. This is the body’s way of communicating to its cells to import the digested glucose from the meal, now circulating in the bloodstream, across their membrane borders to be used as fuel. As time elapses following a meal and cells continue to import glucose, the concentration of circulating glucose will correspondingly decline, leaving less need for insulin’s presence. After enough time has passed, the insulin levels will decline substantially to levels with a normal fasting range.

By contrast, insulin resistance individuals must secrete significantly more insulin to achieve similar levels of glucose depletion from their bloodstream. This means that circulating insulin levels will remain higher than in a non-IR individual, even in a fasted state.

To prepare for a fasting insulin test, patients will be instructed not to eat any food for a period of time, usually 8 – 12 hours, after which a blood sample will be taken and analyzed. Depending on whether the insulin levels fall within a normal range (generally up to 25 µU/mL), doctors will use this information as part of their assessment of a patient’s insulin responsiveness.

Often, doctors will perform a fasting insulin test in conjunction with a fasting glucose test in order to improve the accuracy of their diagnosis. Researchers have developed a mathematical formula to combine the results of both these tests for a more accurate determination of a patient’s IR status. The results of this formula are called the HOMA-IR score and can be very useful as part of the overall diagnostic procedure.

Oral glucose tolerance

Yet another diagnostic tool in a doctor’s toolkit is the oral glucose tolerance test, or OGTT. This test is typically performed after fasting insulin and glucose have already been measured. Simply put, the OGTT seeks to establish how well your body responds to a sudden influx of glucose.

Again, this test takes advantage of known differences in the capacities for glucose metabolism of insulin resistance and non-IR individuals. Because IR individuals do not respond as well to the presence of insulin, doctors expect to see a more gradual decline in blood sugar following an influx of glucose than they would in a non-IR patient.

The test itself is quite simple. In a fasted state, the patient will be given a sweet substance to ingest. The substance contains a known amount of sugar, which allows the doctors to predict how the patient’s body should respond given their body mass and other factors. Blood glucose measurements will be taken and analyzed at regular intervals following the test, typically every half-hour for a total of 3 hours.

Different practitioners may vary in their interpretation of OGTT results, but a general expectation for a non-IR individual is for their blood glucose to return to baseline over the course of the test. High blood glucose levels after several hours may indicate to doctors that the patient has some level of impairment in their sensitivity to insulin.

So, you have insulin resistance: What Now?

Being diagnosed with a medical condition is never pleasant. However, discovering that you have IR can actually have a silver lining. Because insulin resistance often develops into more serious complications like type 2 diabetes, intervening before the condition progresses can often delay or resolve the possibility of further complications.

The most important thing a patient should do after receiving an IR diagnosis is to speak to their healthcare provider and develop a plan for treating the condition. Each individual’s case will vary, so it’s important to develop an approach with your doctor that suits your individual needs. In some cases, that may involve taking prescribed medications to help regulate your glucose metabolism and insulin sensitivity.

With that said, there are numerous lifestyle modifications that can also prove helpful in reducing the significance of insulin resistance in your life. The most common changes prescribed to individuals with insulin resistance will involve modifying diet, activity levels, and stress management, in order to reduce the environmental factors that contribute to insulin resistance. The details of these interventions are beyond the scope of this article, but consider consulting with your doctor about how best to ensure you are living an IR-friendly lifestyle.