Insulin Resistance Vs. Prediabetes: What You Need To Know

Understanding the nuances between insulin resistance and prediabetes is essential in the context of public health, especially considering that an average of 1 in 3 people in the US grapple with prediabetes and insulin resistance. 

This article explores the relationship between these conditions and their diagnostic differences and suggests lifestyle changes that may help manage their impact. By fostering understanding, it encourages individuals to take steps towards supporting better metabolic health.

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What Is Insulin Resistance?

Insulin is a hormone released by the pancreas that helps to maintain healthy blood sugar levels by moving excess glucose out of the blood and storing it in muscle tissue. It also reduces glucose production in the liver when overall blood sugar levels are adequate. 

Insulin resistance is a condition in which these processes are disrupted due to the inability of cells to respond to insulin's signals effectively. If prolonged, insulin resistance can eventually contribute to metabolic disorders such as type 2 diabetes and non-alcoholic fatty liver disease (NAFLD).

Causes and Risk Factors

Common causes and risk factors for insulin resistance include:

• Physical inactivity
• Increased weight gain, especially in the abdomen
• Nutritional imbalances
• High sodium diets
• Advanced age
• Certain medications, such as glucocorticoids
• Genetic conditions such as polycystic ovarian syndrome
• Associated metabolic conditions such as NAFLD, obesity, and prediabetes

What Is Prediabetes?

Prediabetes is a condition in which blood sugar levels are elevated above normal but not to a high enough threshold to be diagnosed as type 2 diabetes. In prediabetes, the pancreas may struggle to produce enough insulin to regulate blood sugar levels within the body, leading to high blood glucose. It is often found incidentally as part of a routine screening lab work or is identified using an oral glucose tolerance test. 

Diagnostic parameters for prediabetes are as follows:

• 12-hour fasting blood glucose: 100 mg/dL to 125 mg/dL
• Hemoglobin A1c: 5.7% to 6.4%
• Oral glucose tolerance test: 140 mg/dL to 199 mg/dL

Although often viewed as a precursor to type 2 diabetes, prediabetes is in itself a condition that affects blood sugar regulation, pancreatic function, vascular health, kidney health, and inflammation. It has been linked to increased risk for cardiovascular disease, cancer, and dementia, even in cases that do not progress to full-blown diabetes (19). 

Insulin Resistance & Prediabetes: What Is The Connection?

Insulin resistance is often the first step along the pathway to type 2 diabetes and other metabolic conditions, with prediabetes often following as the condition progresses. 

During insulin resistance, the muscle and liver cells may not respond to insulin signals effectively, leading to temporary elevations in blood sugar. The pancreas responds by producing more insulin to help return blood sugar levels to a healthy range.

In contrast, in prediabetes, the pancreas may reach a point when it can no longer produce enough insulin to maintain blood sugar balance, resulting in persistent blood glucose dysregulation (33). 

Generally, insulin resistance may precede the development of type 2 diabetes by 10-15 years, while prediabetes may precede diabetes by 5 years. 

Insulin Resistance Vs. Prediabetes: Key Differences

The main difference between insulin resistance and prediabetes is in regard to pancreatic function. 

• In insulin resistance, although pancreatic processes are increased, they may still manage blood sugar levels effectively. 
• In prediabetes, pancreatic cells may no longer compensate for reduced insulin sensitivity, resulting in persistent elevations in blood sugar. 

Clinically, prediabetes is easier to identify and monitor as blood glucose tests such as fasting blood glucose and hemoglobin A1c will show up as abnormal.  In insulin resistance, these may still fall within the normal range. 

Routine testing for insulin resistance is not performed by most healthcare providers as direct markers are often complicated and expensive, though surrogate markers such as fasting insulin and HOMA-IR are sometimes used. Instead, diagnosis often occurs in later stages when insulin resistance is already accompanied by related metabolic conditions. 

The overall consequence is that prediabetes offers a clinical intervention point to help manage progression, whereas insulin resistance usually goes unnoticed and untreated even though it may be more easily managed with lifestyle changes. 

Signs and Symptoms

Insulin resistance can often be asymptomatic, but its presence is more likely when the following are present: 

• High blood pressure
• Elevated levels of cholesterol and triglycerides
• Increased waist circumference
• Darkened patches of the skin, especially around the neck, armpit, and groin
• Polycystic ovarian syndrome

Similar to insulin resistance, most people with prediabetes do not develop symptoms. However, those who are symptomatic can present with the following:

• Increased hunger
• Weight gain
• Fatigue
• Weakness
• Blurry vision
• Cuts or bruises that take long to heal

Because prediabetes is not often accompanied by noticeable symptoms, it is important that it be regularly screened via laboratory testing for those at risk. 

Prevention and Management

Both prediabetes and insulin resistance are highly associated with physical inactivity and overweight status. Therefore, lifestyle interventions are at the cornerstone of supporting the management of these conditions. 

• Diets, such as the Mediterranean diet that prioritize high fiber intake from fruits and vegetables, whole grains, lean proteins, and fats that limit processed foods and sweets, are associated with decreased risk of type 2 diabetes and improved glycemic control (20). 
• Additionally, regular aerobic exercise has been shown to support healthy fasting blood glucose and hemoglobin A1c levels, reduce central obesity, and increase insulin sensitivity in patients with prediabetes and insulin resistance. 

When to See a Doctor

The US Preventive Services Task Force recommends screening annually for prediabetes and type 2 diabetes in individuals who are overweight and between the ages of 35 and 70. No official screening guidelines exist for insulin resistance. 

Signs of Worsening Conditions

Patients who are symptomatic or have multiple risk factors for prediabetes and insulin resistance should consult with their healthcare provider, as catching these conditions early can help manage their progression into more serious diseases. 

If the following symptoms develop, immediate medical attention is warranted as type 2 diabetes may be likely:

• Frequent urination
• Extreme hunger and/or thirst
• Fatigue
• Blurred vision
• Slow healing of cuts and bruises
• Numbness and tingling in the hands and feet
• Unexpected weight loss

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Key Takeaways

• Identifying insulin resistance and prediabetes is vital for early intervention and prevention. Understanding their connection can help guide individuals towards better metabolic health. 
• Insulin resistance occurs when there is impairment in insulin signaling. This leads to higher than normal output of insulin from the pancreas to help manage blood glucose levels.
• Prediabetes is a condition in which the pancreas increases insulin secretion but may not effectively lower blood glucose levels, resulting in sustained elevations of blood sugar. 
• Both conditions have important health implications, including increased risk for the development of diabetes.
• Lifestyle adjustments, such as diet and exercise, play pivotal roles in managing these conditions. By heeding warning signs, undergoing regular screenings, and adopting healthy habits, individuals can support their health and pave the way toward a healthier future.