By Kathleen Regan, ND

What is ‘blood sugar’?

Blood sugar is the amount of glucose or sugar found in your blood.

Is it normal to have sugar in the blood?

A certain level of sugar is normal in the blood. Our body has developed ways of controlling sugars so that they aren’t too high or too low. A number of things will cause sugar to be released into the blood including food, drink, exercise, stress, dehydration, illness or infection. We use sugar as an energy source. Any signal that the body requires energy can stimulate the release of glucose from our own bodily supply.

How do I know if my blood sugar is too high?

There are several signs that blood sugar is too high including:
• increased thirst and a dry mouth,
• needing to pee frequently,
• tiredness,
• blurred vision,
• headaches,
• unintentional weight loss,
• recurrent infections, such as yeast infections, bladder infections (cystitis) and skin infections.

However, these are signs that blood sugar has been elevated for some time. High levels of sugar in the blood are often diagnosed too late. Our typical measurement, ‘fasting glucose’ or even HemoglobinA1C can be insensitive to early changes that affect our ability to absorb glucose. These tests are somewhat insensitive to a condition called insulin resistance which occurs before impaired glucose absorption (pre-diabetes) or Type II Diabetes.

What is Insulin Resistance?

Type II Diabetes is often described as a lifestyle disease; one that is preventable and often treatable with dietary and lifestyle changes. Yet the problems that lead to diabetes start many years before we see changes in traditional blood work. A preventative approach requires earlier screening and more sensitive cut offs to catch the rise in sugars or the beginning of ‘insulin resistance’.

When you consume sugars, refined carbohydrates and other high glycemic index foods (foods that quickly release high amounts of sugar into your blood), your body produces a hormone called insulin in response to elevated sugars. Insulin helps the cells in your body to absorb the sugars in your blood.

Insulin levels will rise overtime to meet the demand of elevated blood sugar. Eventually the cells stop responding as well to insulin and we are unable to remove glucose from the blood effectively. We call this ‘Insulin Resistance’.

High insulin levels are an earlier sign of insulin resistance and pre-diabetes and may show up long before abnormalities in common screening tests. In fact, elevations in insulin are associated with:

• obesity,
• fatigue after meals,
• sugar cravings,
• abnormal cholesterol,
• high blood pressure,
• increased inflammation,
• some forms of cancer

Understanding Blood Tests for Insulin Resistance & High Blood Sugar

The two tests most commonly run to screen for high blood sugar and diabetes are ‘Fasting Glucose’ and ‘HemoglobinA1C’ or HA1C.

Fasting Glucose: This is a blood test typically done in the morning before you eat or drink anything or after you have fasted for 8-10 hours. It is designed to test for circulating levels of sugar in the blood

HemoglobinA1C or HA1C: This is a measurement of the percentage of hemoglobin to which sugar has bonded due to chronically elevated blood sugar or ‘glycated sugar levels’. It reflects your average blood sugar level over the past three months and is a good long-term measurement of blood sugar control.

Both of these tests have a wide reference range sensitive to detecting pre-diabetes or diabetes. It is possible to apply a preventative approach to health by flagging ‘high-normal’ results rather than waiting until the results become abnormal. Yet, these tests are not sensitive to detecting a growing insulin resistance.

Fasting Insulin Test: This is a blood test typically done in the morning before you eat or drink anything or after you have fasted for 8-10 hours. It is designed to test for circulating levels of insulin in the blood. If insulin remains elevated or at high normal levels despite an overnight fast, we know that the body is becoming more resistant to sugar absorption.

Oral Glucose Tolerance (OGTT) Test: An OGTT takes 2 hours to complete and requires 8 hours of fasting ahead of time. Blood is drawn in the fasting state. You will then consume a sugary liquid. Blood is typically drawn another 2-3x over the next 2 hours. This test also measures fasting insulin and ideally insulin across time. This test is the most sensitive test to identify insulin resistance in ‘real time’ or when you are consuming sugar. We look to see how long it takes for glucose and insulin to return to normal levels.

A fasting insulin test or an OGTT test are not typical tests used to screen for blood sugar imbalance. Yet they are very useful measurements in certain conditions that can be linked to dysregulated blood sugar and insulin resistance.

I recommend a combination of the above tests to anyone experiencing:

• difficulty losing weight,
• fatigue after meals,
• mental fogginess,
• sugar cravings,
• hormone imbalances (such as polycystic ovarian syndrome, infertility, endometriosis, thyroid issues and more),
• abnormal cholesterol,
• high blood pressure,
• increased inflammation
• some forms of cancer

It is important to consult a practitioner who can read these blood tests with a preventative medicine lens. Meaning that they can evaluate the results in terms of optimal function rather than just disease. Just because your fasting glucose or HA1C levels are ‘normal’ it doesn’t mean they are ideal.

In naturopathic medicine, blood sugar testing is considered a basic health screening tool rather than just a tool for diagnosing diabetes. Diabetes doesn’t typically happen over night and the signs can often be read in your lab work years earlier! Detecting these changes earlier makes it much easier to treat with basic diet and lifestyle changes.


1. Umeno A, Fukui T, Hashimoto Y, Kataoka M, Hagihara Y, Nagai H, Horie M, Shichiri M, Yoshino K, Yoshida Y. Early diagnosis of type 2 diabetes based on multiple biomarkers and non-invasive indices. J Clin Biochem Nutr. 2018 Mar;62(2):187-194. doi: 10.3164/jcbn.17-81.

2. Danaei G, Finucane MM, Lu Y, et al. National, regional, and global trends in fasting plasma glucose and diabetes prevalence since 1980: systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2. 7 million participants. Lancet. 2011;378:31–40.

3. Zhang X, Gregg EW, Williamson DF, Barker LE, Thomas W, Bullard KM, Imperatore G, Williams DE, Albright AL. A1C level and future risk of diabetes: a systematic review. Diabetes Care. 2010 Jul;33(7):1665-73.

4. Benhalima K, Minschart C, Ceulemans D, Bogaerts A, Van Der Schueren B, Mathieu C, Devlieger R. Screening and Management of Gestational Diabetes Mellitus after Bariatric Surgery. Nutrients. 2018 Oct 11;10(10)

5. Kolb H, Kempf K, Röhling M, Martin S. Insulin: too much of a good thing is bad. BMC Med. 2020 Aug 21;18(1):224.