High blood sugar has been linked to depression

Blood Sugar Levels and Depression: What’s the Connection?

Blood Sugar Levels and Depression: What’s the Connection?

Scientifically reviewed by: Michael A. Smith, MD

Diabetes is not a diagnosis anyone wants. More than 37 million Americans suffer from this disease, which if not properly managed, can lead to vision loss, heart and kidney disease, inflammation and accelerated aging.

As if that weren't "depressing" enough, a new study by Chinese researchers has added weight to an additional health concern about elevated blood sugar: that it can play a role in mental health disorders such as depression as well.

How are blood sugar and depression related?

The recent analysis involved Chinese scientists looking at data gathered through the UK Biobank study, a large cohort study out of the UK. The researchers analyzed information from 33,151 participants, looking at their HbA1c levels (a measure of average blood sugar levels over time), MRI imaging, and data regarding depression and depressive symptoms.

When researchers mapped the relationships between HbA1c levels, depression and brain imaging, they found higher HbA1c levels were associated with depression. This was no surprise—previous research has shown that people with diabetes are at increased risk of depression.

The novel part was that they also saw HbA1c levels were associated with reduced grey matter volume in the brain—and reduced grey matter volume was also associated with depression.

This association, which was strongest in people over 60, offers evidence of a potential additional link between diabetes and depression. The results suggest that uncontrolled high blood glucose levels (as indicated by HbA1c levels) may damage the brain, leading to reduced cerebral grey matter. This in turn may increase the risk of depression and other mood disorders.

What is depression?

Depression is characterized by symptoms like low mood and a loss of interest in previously pleasurable activities. If depressive symptoms are persistent and interfere with day-to-day function, they may be diagnosed as Major Depressive Disorder or as another mood disorder.

Depression negatively affects your mood, thinking and behavior, and symptoms can vary from mild to severe. To qualify as depression, symptoms must last at least two weeks. Depressive symptoms include:

  • Experiencing sadness or feeling depressed
  • Loss of interest or pleasure in daily activities
  • Appetite changes or weight changes unrelated to dieting
  • Being unable to sleep or sleeping too much
  • Loss of energy or increased feelings of fatigue
  • Increased fidgeting or inability to sit still
  • Slowed movements or speech
  • Feelings of guilt, anxiety or worthlessness
  • Difficulty concentrating or making decisions
  • Thoughts of death or suicide

Similar to depression, anxiety is a mood disorder, and it is characterized by excessive worry or dread, as well as symptoms that may look like depression, such as agitation and restlessness. You can experience symptoms of both anxiety and depression without having a mood disorder. A healthcare provider would be able to provide a diagnosis based on your symptoms and help you take steps to manage your mental health.

Can sugar make you feel depressed?

There is some data that links sugar consumption—such as ice cream and sugary drinks like soda—to depression as well as other negative health effects, such as hair loss, inflammation and much more. There is also research that shows people with diabetes have an increased depression risk.

This doesn't mean that consuming sugar in your diet will give you symptoms of depression, but there definitely is an association between consuming a lot of added sugar, uncontrolled blood sugar levels and depressed mood. Not to mention that when we eat a lot of sweet foods and carbs, we tend to feel anxiety afterward about our lack of self-control, and that can certainly affect mood.

Research has shown dietary added sugars are correlated with mental health in general, and with symptoms of anxiety in particular. Studies have reported the influence of high sugar intake on inflammation, gut microbiome dysbiosis and brain insulin resistance, which are factors underlying anxiety disorders.

Healthy dietary patterns, like the Mediterranean diet, may help decrease your depression risk, according to research. Studies have also linked eating fruits and vegetables to improved mental health.

Can depression cause sugar cravings?

Sure! As many of us have experienced, feelings of sadness, depression, chronic stress and anxiety may cause cravings for comfort food. While emotional eating and cravings are typically associated with chocolate and ice cream, those aren't the only carbohydrates we may crave. The comfort foods we choose generally are full of saturated fats and salt in addition to added sugars.

Even without depression symptoms, many people occasionally eat sweet food to feel better. After all, enjoying your favorite food, or even a cup of coffee, releases dopamine, one of our feel-good neurotransmitters. But uncontrolled emotional eating and stress-related cravings for high-sugar or highly processed foods can contribute to further mental health and physical health issues. After all, diet, mood, stress and metabolic health are all linked, and research shows that high blood sugar—one result of eating high-glycemic foods—contributes to our risk of depression.

So if your sadness has you craving a fresh doughnut or a bowl of ice cream, try reaching for a healthier snack with fewer simple carbs (like added sugars), such as fresh fruit, plain Greek yogurt or dark chocolate (a healthy dopamine booster). These lower-sugar options can dial down those cravings and make a difference in the way you feel, both in mind and in body.

Physical activity is also a good way to curb food cravings, support mental health and encourage long-term whole-body health.

Other reasons to limit your sugar intake

Studies have found too much added sugar may put you at higher risk not only for depression, but also serious medical conditions:

  • Cardiovascular disease.

    High sugar intake can raise blood pressure, cause weight gain and increase chronic inflammation, all of which can lead to heart disease. It is also linked to increased cholesterol and triglyceride levels.
  • Cognitive problems.

    Sugar affects brain health and can contribute to dementia and Alzheimer's disease.
  • Diabetes.

    This disease occurs when your blood glucose, or blood sugar, is too high because of problems with the hormone insulin, which is supposed to move glucose into your cells to be used for energy.
  • Obesity.

    Sugary beverages and hidden added sugars in processed foods have contributed greatly to obesity.
  • Inflammation.

    Sugar consumption has been linked to inflammation, which may contribute to many health conditions.
  • Cancer.

    Specifically, high sugar intake has been linked to risk of various cancers, as well as worse outcomes.

In addition, some evidence suggests that elevated blood sugar levels may be linked to kidney and liver disease, and damage to the retina, muscles and nerves.

And of course, as your dentist probably has been telling you your whole life, too much added sugar may also cause cavities and tooth decay. You may also be warned by your dermatologist that sugar intake can contribute to skin aging and wrinkles. This effect is most likely caused by glycation, and it can speed up the dreaded telltale signs of aging, like crinkly eyes, laugh lines, sagging skin and an overall dull complexion.

Note that these concerns are centered on the added sugars we get from processed foods, not from the natural sugars in fruits and vegetables. The best dietary patterns limit processed foods and promote nutrition from whole food and lightly processed food sources.

Where Does Added Sugar Come From?

Processed and packaged foods are part of modern life, but this is one development that has not been to our benefit. Many people are consuming too much added sugar, and sometimes they don't even know it.

In the standard American diet (sometimes known, aptly, as SAD), the top sources of sugar are soft drinks, fruit drinks, flavored yogurts, cereals, cookies, cakes, candy and most processed foods. But added sugar is also present in items that you may not think of as sweetened, such as soups, bread, cured meats and ketchup. Food manufacturers add sugar to their products to increase flavor or extend shelf life.

As a result, the average adult takes in about 17 teaspoons of added sugar each day, according to the American Heart Association. That's two to three times the daily amount recommended by the AHA. Almost half of that added sugar comes from sugary drinks—not just soda, but fruit juices, energy drinks and those lovely coffee drinks we all enjoy so much! So, the first step in reducing added sugar intake (and reducing inflammation and risk of obesity) is drinking more water in place of sweetened drinks.

How to cut down on excess sugar

Changing your diet to cut down your sugar intake is a matter of making smart choices.

  • Eat plenty of whole fruits and vegetables, which have natural sugars that may help you stop craving processed carbohydrates.
  • Eliminate or reduce the amount of sugar you add to foods and drinks when making your own.
  • Choose nutrient-dense foods and proteins instead of empty calories at mealtimes and snack times.
  • Replace sugary drinks with sugar-free options or water.
  • Read product labels when you shop to find those with less added sugars.



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The Life Extension Health News team delivers accurate information about vitamins, nutrition and aging. Our stories rely on multiple, authoritative sources and experts. We keep our content accurate and trustworthy, by submitting it to a medical reviewer.