top of page

Insulin Resistance, Diabetes, and Functional Medicine

Jonathan Vellinga, MD


Insulin resistance, prediabetes, and diabetes rates continue to rise, according to the CDC (1). Around 34% of the population has either diabetes or prediabetes, and up to 70% of overweight and obese people may have some form of insulin resistance (1, 2). Unfortunately, diabetes is the seventh leading cause of death in the United States (3). While these statistics may seem grim, there is good news: with the help of functional medicine, these conditions can be managed and sometimes even reversed!


Insulin Resistance, Diabetes, and Functional Medicine

What is insulin resistance? And how is insulin resistance different from diabetes?


After you eat, a hormone called insulin helps move glucose from your blood into your cells (4, 5). When your body (specifically the muscles, fat, and liver) doesn’t respond as easily to insulin, too much glucose remains in the blood, resulting in what we call high blood sugar. If this happens consistently and your body is unable to keep your blood sugar levels in check, you are considered insulin resistant (4). Normally, your pancreas will increase insulin production, which can keep blood glucose levels within a relatively normal range (4, 5). If insulin resistance worsens and blood sugar levels remain elevated, then this results in prediabetes. Once glucose levels remain consistently elevated and the disease progresses, you can develop type 2 diabetes (4, 5).


Type 2 diabetes is the more common type of diabetes, in which the body does not respond to insulin well (unlike type 1 diabetes, which only means that the body has stopped making insulin). While both types can be related to an inherited genetic predisposition, both are triggered by different environmental factors. Triggers of type 1 are still being studied, but cold climate, viruses, and early diet (not breastfeeding combined with early introduction of solid foods) are thought to be some of the causes (6). Type 2 diabetes has a much stronger tie to lifestyle, family history, and genetics (6).


When pregnant, some otherwise non-diabetic women can develop gestational diabetes. The body uses insulin less effectively during pregnancy due to hormonal changes (8). For some women who already have insulin resistance, these hormonal changes exacerbate the resistance and cause short-term diabetes (8). Gestational diabetes usually doesn’t have any symptoms and may subside after giving birth. However, about 50% of women with gestational diabetes end up developing type 2 diabetes (8).


What are the symptoms of insulin resistance, prediabetes, and diabetes?


Type 1 and type 2 diabetes symptoms vary and can be mild or very severe. Symptoms can include (4, 7):

  • Extreme thirst, hunger, or fatigue

  • Frequent urination

  • Losing weight without trying

  • Delayed healing time

  • Dry, itchy skin

  • Tingling or loss of feeling in feet

  • Blurry eyesight

  • Increased infections

  • Nausea, vomiting, stomach pains (type 1 only)


Unfortunately, insulin resistance, prediabetes, and gestational diabetes often don’t have any symptoms and may remain asymptomatic for many years. Some people with prediabetes experience darkened skin in the armpit or on the back and sides of the neck and may have skin tags in the same area (4). While rarer, prediabetes and diabetes can also cause eye changes that eventually lead to problems with eyesight (4).


The more common asymptomatic state of insulin resistance and prediabetes underscores the importance of regular screening with your medical provider.


Risk Factors


Unfortunately, both genetics and lifestyle can add to the risk of developing insulin resistance, prediabetes, and diabetes, including (4, 14, 15):


  • Being overweight or obese

  • Poor diet

  • Lack of exercise or physical activity

  • Being 45 or older

  • Family history of diabetes, especially within the immediate family

  • High blood pressure or high cholesterol

  • History of heart disease or stroke

  • Polycystic ovary syndrome

  • African American, Asian American, Hispanic/Latino, Pacific Islander, or Native Alaskan, American, or Hawaiian ethnicity

  • History of gestational diabetes

  • Hormonal disorders, including imbalanced female sex hormones

  • Sleep problems, including sleep apnea

  • Toxin exposure.

  • Inflammation.

  • Chronic stress


Potential Complications


Once you discover that you or a loved one has diabetes, the goal is to manage diabetes as effectively as possible. However, having diabetes long-term often brings complications, especially if it is not well-controlled. Diabetes greatly increases the risk of cardiovascular problems and diseases, such as angina, heart attack, stroke, and atherosclerosis (narrowed arteries) (9). It may also cause many types of damage, including nerve, kidney, eye, and foot damage. Nerve damage may affect the gut and reproductive systems, causing gastrointestinal problems or erectile dysfunction. Hearing impairment and skin conditions are also more common (9).


Insulin resistance and diabetes have a strong effect on the brain. The brain also becomes insulin resistant, and its cells work less effectively (10). Neuroinflammation, reduced neural connectivity, and brain atrophy may then occur (10, 11). Diabetes is linked to degenerative brain diseases, such as Alzheimer’s, Parkinson’s, and Huntington’s disease, and the link between Alzheimer’s and diabetes is especially strong (9, 10). Unfortunately, diabetes is also considered a risk factor for mood disorders such as anxiety and depression (9, 10, 11). It is clear that carefully preventing and managing insulin and blood sugar levels is critical to maintaining optimal brain health as we age.


When a mother has gestational diabetes, it does not result in the baby also having diabetes, although it may cause the baby to grow excessively, have low blood sugar, or be at risk for type 2 diabetes later in life. In rare cases, it may cause the baby’s death or preeclampsia in the mother (9).