What Is Insulin Resistance (and How Do You Treat It)?

By now, you’ve probably heard the term “insulin resistance” when it comes to PCOS, weight gain, blood sugar, or diabetes. But what is insulin resistance, and why does it impact fertility?

Insulin is a hormone produced by the pancreas that brings sugar from your bloodstream into your cells for energy. Think of insulin as the key that unlocks the door for glucose from food to get into the cell to make energy.

Insulin resistance happens when cells no longer respond normally to insulin—the key isn’t working, and the glucose is trapped outside of the cell in the bloodstream instead of being used inside the cell for fuel. Your body compensates by making more and more insulin to keep blood sugar levels stable. If this increase in insulin production continues over a long period, it can impact hormone balance, metabolism, inflammation, egg quality, ovulation, sperm quality, and long-term health risks.

There are 2 types of diabetes: 

• Type 1 diabetes
• Type 2 diabetes

Type 1 diabetes is an autoimmune condition where your immune system attacks and destroys the insulin-producing cells in the pancreas. It requires lifelong insulin therapy to regulate blood sugar levels because their bodies produce very little or no insulin. There is no cure and no real prevention—you just don’t produce enough insulin to maintain healthy glucose levels. 

Type 2 diabetes is when your cells become less responsive to insulin over time, leading to high insulin and blood sugar levels. Type 2 diabetes involves genetics, body composition, stress, sleep, nutrition, and exercise, all of which contribute to the development of insulin resistance.

About 70% of individuals with Polyendocrine Metabolic Ovarian Syndrome (PMOS, formerly PCOS) are affected by insulin resistance. While the body’s cells become less responsive to insulin, the ovaries can remain highly sensitive to it. Elevated insulin stimulates the ovaries to produce more androgens (male-type hormones like testosterone), and interferes with normal follicle development and ovulation, which contributes to symptoms like:

• Irregular or skipped periods

• Jawline acne

• Hair growth in unwanted areas (chin, cheeks, chest)

• Poor ovulation

• Weight gain and difficulty losing weight

This is why supporting blood sugar stability is a foundational part of PCOS care.

Insulin resistance is on the rise, affecting people of all body sizes. Weight can play a role, but it isn’t the whole story. There isn’t one single cause; rather, it's influenced by a combination of factors:

• Chronic stress

• Hustle culture and overwork

• Poor sleep quality

• A lack of exercise

• Low muscle mass

• Diets high in processed foods and low in fibre and protein

• Genetics and family history 

• PCOS

• Exposure to endocrine-disrupting chemicals

• Chronic inflammation

• Smoking

• Hormonal changes around menopause

This is where things get a little nuanced because insulin can be elevated long before glucose levels change. Depending on the situation, healthcare providers would take a look at:

• Bloodwork: Fasting glucose, Hemoglobin A1c, Fasting insulin, Cholesterol, Liver enzymes, Inflammation markers, Hormonal patterns, Oral glucose tolerance testing, Insulin challenge test

• HOMA-IR (a calculation using glucose and insulin)

• Waist circumference

Some people have no obvious symptoms at all, but when symptoms do occur, they may include:

• General fatigue, energy crashes after meals

• Hunger and cravings

• Mood swings with skipped meals (hangry, anyone?)

• Difficulty losing weight

• Brain fog

• Skin tags

• Darkened areas of skin around skin folds (called acanthosis nigricans)

• Irregular periods

• Fertility struggles

• Acne

Using these symptoms as clues to drive further investigations can be very useful.

Good news! Insulin resistance can improve significantly with supportive lifestyle and medical interventions. The goal is to improve how sensitive your cells are to insulin over time, and research consistently shows that exercise, nutrition changes, sleep support, weight management (where appropriate), and supplementation can make drastic improvements to insulin sensitivity.

Sustainable, consistent changes work better than overly restrictive approaches that are hard to maintain and feel like a chore.

Insulin resistance can negatively affect fertility in both males and females.

Sperm health and quality are the big topics here. Studies have found there to be a relationship between insulin resistance and:

• Lower sperm motility

• Increased oxidative stress

• Hormonal imbalances

• Reduced testosterone levels 

Insulin resistance interferes with ovulation and hormone signalling, especially in those with PCOS. Higher insulin levels can contribute to:

• Irregular ovulation

• Poor egg quality

• Increased miscarriage risk

• Hormonal imbalances

• Poorer IVF outcomes

Managing insulin resistance often requires taking stock of and managing a few elements of your day-to-day habits, including nutrition, movement, sleep, supplements, medication, and more.

There is no single “perfect” diet for insulin resistance. Overly restrictive eating backfires in the long term, and research supports eating patterns that keep blood sugar levels stable, which is what improves insulin sensitivity over time. 

This often includes building meals that are satisfying and sustainable with:

• Enough protein (0.8-2g of protein per kg of body weight)

• Enough fiber (Females: ~25g/d, males: ~38g/d)

• Complex carbohydrates over simple carbohydrates: complex carbohydrates such as vegetables (that are low-glycemic and high fiber), legumes, whole grains, and fibre-rich foods are digested slowly and give rise to steadier energy by reducing the spikes and crashes in blood sugar levels

• Mediterranean-style eating patterns with an emphasis on lean meats, vegetables, fibre-rich carbohydrates, healthy fats, legumes, nuts, seeds, and minimally processed whole foods

Aim for 3 to 4 hours per week of exercises like weightlifting or interval training, along with regular walking.

• Strength training and building muscle (muscle mops up extra glucose in the blood), especially of the glutes, hamstrings, and quadriceps (the lower body has the largest muscle groups)

• High intensity interval training (HIIT)

• Sprint interval training (SIT) 

• Walking for 20 minutes after a meal

Supporting sleep quality and stress management can help. Sleep deprivation and chronic stress are associated with blood sugar dysregulation, more hunger and cravings, higher cortisol levels, and changes in the hormones that regulate appetite.

Supplements can help manage insulin sensitivity, usually by balancing hormones or addressing nutrient deficiencies. Here are a few that may help:

• Myo-inositol and D-chiro-inositol

• NAC

• Magnesium

• Berberine

• Chromium

• Ceylon cinnamon

• CoQ10

• Vit D+K2

• Omega 3

Metformin is a medication commonly used for type 2 diabetes, but it is frequently prescribed for PCOS because of the insulin resistance piece. Research suggests metformin may help with:

• Blood sugar regulation

• Ovulation in PCOS

• Reducing insulin levels

• Supporting metabolic health

Metformin is safe in pregnancy, making this a great option for certain individuals whose insulin sensitivity and poor glucose regulation are affecting fertility outcomes. That said, like anything, it may not be appropriate or necessary for everyone, as side effects include nausea or digestive upset, so treatment decisions should always be individualized.

Ozempic is a GLP-1 receptor agonist. GLP-1’s help to regulate blood sugar, slow stomach emptying, and increase feelings of fullness after eating. They improve insulin sensitivity through weight loss and blood sugar regulation. Research shows that GLP-1 medications may have benefits for insulin resistance and PCOS in some individuals, but they’re not a magic fix because they do not replace the foundational lifestyle factors like nutrition, movement, sleep, and stress management, which make a huge difference in moving the needle.