The Link Between Insulin Resistance and Infertility

What is Insulin Resistance (IR)? 

Insulin Resistance (IR) is the beginning of your tissues not adequately responding to insulin leading to reduced blood glucose control. Eventually, if untreated, this will lead to type 2 diabetes. IR can show up decades before diabetes, so early detection means that we can prevent this progression and reduce the risk of gestational diabetes during pregnancy. 

Okay, but you're not pregnant and don't care about diabetes right now. Well, high insulin on its own (in the absence of high blood glucose and overt diabetes) can alter hormones that are important for reproduction. This includes: 

• Testosterone 

• DHT (the more active form of testosterone)

• Estrogen 

• Cholesterol (yes, healthy levels of cholesterol are important for reproduction!)

AND has a significant impact on common fertility outcomes...

How Insulin Resistance Impacts Fertility

Insulin resistance is associated with multiple common fertility concerns including: 

• Ovulatory Dysfunction (check out this blog to help you determine your ovulatory window)  

• Delayed Time to Conception

• Implantation Failure

• Chemical Pregnancy

• Recurrent Pregnancy Loss

• Adverse Pregnancy Outcomes (like gestational diabetes)

• Unexplained Infertility 

Do any of these sound familiar? Then it's time to understand what your blood sugar regulation has to do with your ability to get and stay pregnant.

Risk Factors for Insulin Resistance 

I've been assessing all my fertility patients for insulin resistance, it's a simple non-invasive investigation that provides high-quality information and insight into why you're struggling to get (or stay) pregnant. However, certain diagnoses or collections or signs/symptoms increase the likelihood of insulin resistance. If you fall into either of the categories below, I would recommend advocating to be assessed for insulin resistance. 

1/If you have any of the following:  

PCOS

Recurrent pregnancy loss

Implantation failure

High waist circumference

High BMI

Previously unsuccessful IVF

Other signs of metabolic syndrome (lipids, HTN)

History or family history of GDM, T2DM

Unexplained infertility

2/ If you have any of the following signs or symptoms 

Acne

Skin tags 

Menorrhagia (heavy periods)

Irregular Cycles &/or Anovulation

Hair Loss

Fibroids

Non-alcoholic Fatty Liver Disease (NAFLD)

Abdominal Weight Gain (Central Weight Distribution)

High Cholesterol

How to Assess & Diagnose Insulin Resistance

We can use a simple fasting blood test (insulin and glucose) + a calculation called HOMA-IR to determine if you have insulin resistance. 

Why is HOMA-IR important?

HOMA-IR, or Homeostatic Model Assessment of Insulin Resistance, is a valuable tool for assessing insulin resistance. This metric provides insights into an individual's existence and degree of insulin resistance. 

Examining the connection between fasting blood sugar levels and the hormone insulin can show us how your body responds to insulin.

When there is an excess production of insulin, cells may become unresponsive to it, potentially leading to the development of type 2 diabetes and various chronic health conditions.

If you already have had your fasting insulin and glucose tested you can calculate your HOMA-IR, using the following link!

HOMA-IR Calculator

Interpreting the Results - Optimal Range: 1.0 (0.5–1.4) 

• Less than 1.0 means you are insulin-sensitive which is optimal. (I want to see it at least below 1.7) 

• Above 1.9 indicates early insulin resistance.

• Above 2.9 indicates significant insulin resistance.

A reminder of why this is so important: Participants with HOMA-IR >2 had significantly lower implantation, clinical pregnancy and ongoing pregnancy rates compared to those with HOMA-IR <2. 

Other methods for assessing insulin and glucose regulation include: 

1. Serum HbA1c (although this is less sensitive and may miss the early stages of insulin resistance) 

2. Oral Glucose Tolerance Test 

3. Continuous Blood Glucose Monitoring

So you have Insulin Resistance, Now What?

The good news is that lifestyle change is HIGHLY effective at improving insulin levels and restoring sensitivity. What kind of lifestyle change? 

EXERCISE - exercise improves insulin sensitivity by 50% for up to 72 hours after the last exercise bout. Regular exercise is an important factor in insulin control. Ideally, this is daily (or almost daily) and can be either 30-60 minutes/day intentional workout or a cumulative 30-60 minutes of 'exercise snacks' and interrupting sitting through the day. 

• We want to achieve at least 30 minutes, 5x/week of combination aerobic (walking, running, cycling, swimming, dancing) and resistance training (weight lifting, body weight exercise) 

• Moving before and after meals has also shown benefit in improving blood sugar control in people with insulin resistance (a great time to implement the 'exercise snacks')

DIET - the quality of the carbs you eat matters! We want to focus on LOW GLYCEMIC INDEX carbohydrates. These are fibre-filled carbs like legumes (lentils, chickpeas, black beans), leafy greens, brown rice, quinoa, millet, oats, and whole-grain options. 

• Higher whole grain intake was associated with a higher probability of implantation and live birth rates in an IVF study (dose-dependent increase). We want to try and achieve >50g of whole grain/day

• High glycemic index carbs (white bread, pasta, potatoes), sugar and low fibre diets are associated with delayed time to conception or reduced fecundability in North American and Danish women

SLEEP - sleep deprivation, often studied in shift workers, has been associated with obesity, insulin resistance, and increased risk of Type 2 Diabetes Mellitus and Metabolic Syndrome. 

• When we extend periods of sleep in people with habitual sleep deprivation we see benefit to insulin sensitivity! We see reduced fasting insulin levels inversely correlated to total sleep time (as your time asleep goes up, your fasting insulin goes down). HOWEVER, too much sleep can start to negatively impact insulin sensitivity as well. We're aiming for the golden 7-9 hours/night.

Insulin resistance can have a significant impact on our ability to get and stay pregnant. Testing for insulin resistance is inexpensive and non-invasive and has simple solutions that are highly effective. If you're on a fertility journey and haven't been tested for insulin resistance, it's time to have this conversation with your healthcare provider.