The Hidden Impacts of Blood Sugar Imbalances and Insulin Resistance
Insulin resistance is a silent disruptor that can significantly impact every system in your body, from your brain to energy to your immune system, in ways that are often underappreciated. This invisible force can negatively affect your energy, mood, hormonal balance, and even the health of your skin. This is the surprising stealth nature of insulin resistance, a condition far beyond its normally recognized sequelae of blood sugar spikes, weight gain, and diabetes.
Conventional medicine typically waits until specific markers are significantly out of range to diagnose pre-diabetes or diabetes. However, many individuals begin to manifest functional abnormalities with more nuanced symptoms and test findings many years prior. These people are frequently unaware that they are insulin resistant, and often experience vague symptoms that they attribute to other causes. Yet even in the realm of functional medicine, I’ve found it fairly common for patients to be surprised or even shocked at the discovery of their metabolic dysfunction. Let’s explore what insulin resistance is and the common yet lesser-known ways insulin resistance affects people’s health every day with the top ten hidden impacts of insulin resistance.
What is Insulin Resistance
Insulin is a hormone that helps move glucose from the bloodstream into cells where it’s used for energy. Insulin resistance is when the body’s cells (liver, muscle, and adipose tissue) stop responding properly to insulin, even when normal levels of the hormone are present. When cells don’t effectively respond to insulin (and become resistant) they cannot as easily absorb glucose and its levels build up in the blood. The development of insulin resistance can be due to several factors, though the most common are diet and lifestyle-related such as high sugar diets, chronic stress, and inactivity which leads to inflammation and changes in the cell receptors. Over time, elevated blood sugar levels can raise the risk of type 2 diabetes in addition to contributing to the other health issues and symptoms mentioned below.
Mental Health (depression, anxiety, mood swings)
Did you know that blood sugar imbalances are the number one cause of daily mood swings and that most people completely miss this as a cause? Dysglycemia (a broad term that refers to an abnormality in blood sugar stability) can significantly impact mental health, influencing mood swings, anxiety, and depression through several interconnected pathways.
First, it disrupts glucose uptake in the brain, leading to reduced energy availability for neurons, which affects neurotransmitter production, including serotonin and dopamine, critical for mood regulation. Second, insulin resistance is linked to increased inflammation, which can extend to the brain, contributing to neuroinflammation that is associated with depression and anxiety. It also dysregulates the hypothalamic-pituitary-adrenal (HPA) axis, the body’s central stress-response system, leading to elevated cortisol levels that can worsen mood disorders.
A recent study by researchers from Stanford University showed that insulin resistance doubled the risk of major depressive disorder even in people with no prior mental health diagnoses. Key metabolic markers associated with insulin resistance—such as high triglycerides, low HDL (good cholesterol), and elevated blood glucose—were strongly correlated with the later onset of depression, anxiety, and stress-related disorders.¹
Blood sugar imbalances can also lead to sleep disruption (more on this below), and this can have its own negative effect on mood and anxiety.
Hormone Disruption:
Insulin resistance can have a big impact on reproductive hormones, especially estrogen and testosterone. When insulin levels are chronically high, it can increase androgen (male hormone) levels in women, which throws off the balance of estrogen and progesterone. This is a major factor behind polycystic ovary syndrome (PCOS), a condition marked by irregular menstrual cycles, infertility, mood swings, and other symptoms. In men, insulin resistance is often associated with lower testosterone levels, which can lead to low energy, reduced libido (sex drive and erection), and even mood changes like irritability or depression. This is why addressing blood sugar and insulin levels is a critical and foundational aspect of balancing hormones in a functional medicine model.
Skin & Hair Changes:
Once you understand that insulin resistance causes hormone disruption, it makes sense that it would have an impact on hair & skin, yet the direct correlation is often overlooked. It’s very common for women with PCOS to struggle with skin-related conditions like acne in addition to hair thinning since elevated insulin can lead to increased androgen levels. Increased androgen production results in higher sebum (oil) production in the skin and the growth of finer, more brittle hair on the scalp.
In addition to androgen issues, insulin resistance is associated with oxidative stress, which damages cells, including those in the skin and hair. This damage can lead to premature aging, wrinkles, and loss of elasticity in the skin. Lastly, insulin resistance is associated with specific skin conditions like acanthosis nigricans, a condition where areas of the skin become darkened, and thickened, often appearing on the neck, armpits, groin, and under the breasts. High insulin is also associated with the development of skin tags (acrochordons). High insulin levels in the blood stimulate the production of insulin-like growth factor (IGF-1). IGF-1 promotes cell growth and replication, which may lead to the formation of excess skin tissue, resulting in skin tags.
Energy Levels:
Fatigue is one of the most common symptoms I see when patients experience blood sugar spikes after eating. When you eat a meal high in carbs, especially sugary or starchy foods, your blood sugar can spike quickly. This causes your body to release a lot of insulin to bring those sugar levels down. Sometimes, it releases so much insulin that your blood sugar drops too fast, causing a “sugar crash.” This drop makes you feel tired and sluggish, almost like you’re running low on energy.
Eventually, repeated blood sugar spikes and drops can impair mitochondrial function. Mitochondria are the cell’s powerhouse, producing energy in the form of ATP (adenosine triphosphate). In a healthy state, insulin signals cells to absorb glucose from the bloodstream for energy production. However, in insulin-resistant cells, this process is disrupted, meaning less glucose is available for mitochondria to convert into energy. Over time, this may lead to mitochondrial dysfunction and reduced ATP production, resulting in lower energy levels and increased fatigue regularly.
In addition to affecting mitochondria, blood sugar spikes, and insulin resistance can cause fatigue through several other mechanisms. For one, high blood sugar triggers inflammation, which leads to oxidative stress and the release of pro-inflammatory cytokines—immune signaling molecules that can make you feel tired and generally unwell. Furthermore, elevated blood sugar causes the kidneys to work harder to remove excess glucose, leading to more frequent urination. This process can create mild dehydration and disrupt electrolyte balance, both of which can leave you feeling drained and weak.
Brain Health & Cognitive Impairment:
So far I’ve discussed mood swings and fatigue, which are two of the most common symptoms patients quickly experience throughout their day if they're struggling with insulin resistance. Insulin resistance also impacts brain health and cognition causing brain fog and difficulty with focus and attention. This is due to insulin’s key roles in neuronal communication, memory formation, and learning processes.
When brain cells become insulin-resistant, they struggle to absorb glucose efficiently, leading to reduced cellular energy, which can impair mental clarity, focus, and memory retention. This lack of glucose availability can result in symptoms like brain fog, confusion, difficulty concentrating, and slower mental processing. Even more concerning is the fact that chronic insulin resistance can gradually lead to more severe cognitive decline and is strongly associated with an increased risk of neurodegenerative diseases, including Alzheimer’s.²
Sleep Disturbances:
Blood sugar imbalances can seriously interfere with restful sleep. When cells become less responsive to insulin, the body struggles to regulate blood sugar levels. Blood sugar fluctuations during the night can trigger stress responses, which release cortisol and adrenaline—the body’s “fight or flight” hormones. Elevated cortisol at night can make it hard to fall or stay asleep, leading to poor sleep quality or even insomnia. I’ve had many patients with sleep issues who I recommended using a CGM (continuous glucose monitor) and we were able to identify hypoglycemic (low blood sugar) episodes that were the primary source of their waking.
Decreased Muscle Mass:
If you’re insulin resistant, your body's ability to properly use insulin becomes impaired, leading to less efficient glucose and amino acid uptake into muscle cells. This not only hampers muscle protein synthesis but also increases the breakdown of muscle proteins. As a result, individuals with insulin resistance may progressively experience gradual muscle loss (sarcopenia). Additionally, insulin resistance is often accompanied by increased levels of circulating cortisol, a stress hormone that further promotes muscle breakdown. Unfortunately, the inability to build or maintain muscle can contribute to a vicious cycle of insulin resistance as muscle tissue is a primary site for glucose disposal, and less muscle means more difficulty in managing blood sugar levels effectively!
Compromised Immune System:
Insulin resistance can significantly impair the immune system, weakening the body’s ability to mount an effective defense against infections. One of the key factors behind this immune dysfunction is the chronic inflammation that accompanies insulin resistance. Elevated insulin and blood glucose levels can activate inflammatory pathways and create a state of chronic low-grade, persistent inflammation. This not only damages tissues but also hinders immune cell function. Specifically, insulin resistance has been shown to impair the activity of T cells, which are crucial for fighting off infections.
Furthermore, people with insulin resistance often experience slower wound healing. Research suggests that hyperglycemia (elevated blood sugar) inhibits key processes in wound repair, such as collagen formation, epithelial regeneration, and angiogenesis. Studies have shown that patients with type 2 diabetes tend to have more frequent and prolonged infections, such as urinary tract infections, respiratory infections, and skin infections.³
Fatty Liver and Heart Disease Risk:
Higher blood sugar and insulin levels signal the liver (and other body sites) to store more fat. Eventually, excess fat buildup in the liver may lead to non-alcoholic fatty liver disease (NAFLD). It’s actually fairly common for non-alcoholic fatty liver disease to be diagnosed before diabetes. NAFLD can cause liver inflammation and damage, which may progress to more serious liver conditions if left unaddressed. Furthermore, because insulin resistance changes how the body metabolizes fat, it can promote plaque buildup in the arteries and is thus a significant risk factor for cardiovascular diseases.
Accelerated Aging:
As insulin resistance worsens, it can speed up aging both inside and out. Chronically high insulin levels create more oxidative stress and inflammation in the body, which fuels the aging process. Oxidative stress happens when there’s an imbalance between free radicals (unstable molecules) and antioxidants, leading to cellular damage. This damage shows up on the skin as a breakdown of collagen and elastin—proteins that keep skin firm and youthful—resulting in wrinkles and sagging. In the brain, inflammation and oxidative stress disrupt pathways responsible for memory and learning, linking insulin resistance to cognitive decline and increased risk of neurodegenerative diseases as mentioned above. Managing blood sugar and insulin levels can be essential for slowing down these aging effects.
Conclusion
Blood sugar imbalances and insulin resistance cause a significant amount of inflammation in various body systems that ultimately impact many aspects of health. Addressing these imbalances early can help reduce inflammation, improve any symptoms mentioned above, and support better long-term health outcomes. If you believe you may be insulin resistant or experiencing the early stages of insulin resistance, it may be worth asking your provider to run more comprehensive testing that includes fasting insulin in addition to fasting glucose and A1c.
At CCFM, we look at an even broader spectrum of metabolic and inflammatory markers that provide a clearer picture of overall metabolic health, helping patients catch insulin resistance sooner and identify ways to reverse it! If you’re interested in getting a more comprehensive view of your metabolism check out CCFM’s ‘Mastering Metabolic Disease’ program or our ‘Functional Medicine Checkup,’ which includes 75+ biomarkers to gain insight into what’s happening in your body!
References:
- Watson KT, Simard JF, Henderson VW, et al. Incident Major Depressive Disorder Predicted by Three Measures of Insulin Resistance: A Dutch Cohort Study. American Journal of Psychiatry. 2021;178(10):914-920. https://doi.org/10.1176/appi.ajp.2021.20101479
- Ferreira LSS, Fernandes CS, Vieira MNN, De Felice FG. Insulin Resistance in Alzheimer’s Disease. Frontiers in Neuroscience. 2018;12. doi:https://doi.org/10.3389/fnins.2018.00830
- Geng K, Ma X, Jiang Z, et al. Innate Immunity in Diabetic Wound Healing: Focus on the Mastermind Hidden in Chronic Inflammatory. Frontiers in Pharmacology. 2021;12. https://doi.org/10.3389/fphar.2021.653940
