Here’s What You Need to Know About A1C
During routine lab tests, many otherwise healthy people are surprised to learn their hemoglobin A1C — a snapshot of their average blood-sugar level over the past few months — is higher than it should be. Depending on the number, this could mean a diagnosis of type 2 diabetes or its more common precursor, prediabetes, a condition in which blood-glucose levels run high but don’t qualify as diabetes just yet.
According to the Centers for Disease Control and Prevention (CDC), 38.4 million Americans live with diabetes. More than 90 percent have type 2, the version that’s usually associated with lifestyle factors (though genetics can play a role); only 5 to 10 percent represent those with type 1, an autoimmune condition. And an estimated 97.6 million American adults — that’s nearly 38 percent — have prediabetes.
Neither a prediabetes nor type 2 diagnosis is welcome news, but plenty of evidence supports the use of diet and lifestyle strategies for course correction. Prediabetes, especially, can be a useful wake-up call.
“There’s so much that people can do in the prediabetes stage to prevent progression into type 2 diabetes,” says Elizabeth Boham, MD, MS, RD, a functional-medicine physician in Lenox, Mass.
The right strategies may not only prevent A1C levels from rising further, but they can also help lower them into a healthy range. And there are many reasons to make that a priority, Boham notes. “Even prediabetes that never turns into diabetes increases risk of heart disease, multiple cancers, dementia, stroke, weight gain, and fatigue.”
What Is A1C?
Our bodies are constantly working to keep our blood-sugar levels in a healthy range. This helps ensure our cells receive a steady supply of energy. Yet sometimes the complex interplay of hormones and other physiological processes — as well as the quantity, quality, and timing of the food we eat — destabilizes these levels.
If blood glucose falls too low, we may feel dizzy, fatigued, and shaky, or we may even pass out. High blood sugar — a hallmark of diabetes — can lead to extreme thirst, excessive urination, blurred vision, nausea, and headaches. If high blood sugar becomes chronic, it can result in nerve and organ damage, heart disease, and stroke.
Routine lab work during a doctor’s visit often includes a fasting glucose test; this measures how much glucose remains in the blood after an eight-hour fast. A level less than 100 milligrams per deciliter is considered normal. A higher reading might prompt your doctor to order an A1C test, which reveals the body’s blood-glucose levels over time.
Here’s how the test works: Glucose binds to hemoglobin, a protein in red blood cells that carries oxygen throughout the body, in a process called glycation. The A1C test measures the percentage of hemoglobin that is glycated.
Because red blood cells live for about three months, the test reflects the average blood-glucose levels over that period. “The higher your blood sugar is, and the longer it is high, the higher your A1C will be,” explains Jill Weisenberger, MS, RDN, author of Prediabetes: A Complete Guide.
An A1C level below 5.7 percent is considered normal. A level of 5.7 to 6.4 percent is classified as prediabetes, and a level of 6.5 percent or higher indicates diabetes.
Insulin Resistance Explained
If the body’s ability to regulate blood sugar is routinely strained by trying to digest high-glycemic foods or by an excess of visceral fat, this can lead to insulin resistance.
Insulin is a hormone the pancreas produces to help regulate blood sugar. It ushers glucose from the blood into cells in the muscle, fat, and liver, where it can be used for energy. If those cells reach their glucose-carrying capacity, they stop responding to insulin. Picture them hanging a No Vacancy sign and ignoring the insulin knocking at the door.
When this happens, excess glucose stays in the bloodstream, and the pancreas pumps out increasing amounts of insulin, trying to overcome the resistance in the muscle, fat, and liver cells. Eventually, the pancreas can’t keep up with the demand for insulin, and blood sugar rises even higher.
“The way to understand insulin resistance, prediabetes, and diabetes is that it’s the same essential problem, which is that your body has too much sugar,” explains nephrologist Jason Fung, MD, author of The Diabetes Code. “When you put food in the refrigerator to eat later on, you can reach a point where you have too much food. Similarly, if we put too much glucose into storage, when we get more, it can’t get into the cell and it stays out in the blood.”
Unfortunately, it’s still possible to have issues with insulin even if your blood sugar is in a healthy range. “The body works really, really hard to keep blood sugar normalized,” Boham notes. “Someone’s blood sugar might look completely normal because they’re producing two, three, four times the usual amount of insulin to regulate it.”
Excessive production of insulin can create its own problems, including weight gain, fatigue, and fatty liver. (Nonalcoholic fatty liver disease affects up to a third of Americans, taking a toll on our collective health. See “The Hidden Liver Crisis” to learn more.) “Insulin is a storage hormone,” Boham explains. It causes fat to accumulate, particularly around the midsection. “That fat is an active organ that’s producing a lot of inflammatory markers. These markers can drive a vicious cycle of inflammation and further weight gain.”
Because blood-glucose readings may not reveal simmering insulin resistance, Boham looks for other clues. Waist-to-hip ratio is a useful tool to measure belly fat, a hallmark of the condition. Ideally, the ratio should be 0.9 or lower for men and 0.8 or lower for women, though certain ethnicities may be at risk with lower ratios (more on the role of genetics later).
In women, irregular periods, hair growth on the lower face, and hair loss on the head can also signal issues with insulin sensitivity. Other warning signs for everyone include skin tags in the armpits or around the neck; acne; and dark, velvety patches of skin on the neck, armpits, or groin.
The Growing Challenge of Type 2 Diabetes
The CDC estimates that 10.3 percent of American adults were living with a form of diabetes between 2001 and 2004. That number rose to 13.2 percent for 2017 to 2020. Combined with the estimated 38 percent of American adults who meet the criteria for prediabetes, more than half the adult population now has some version of the disease.
Type 2 diabetes in particular has become a global problem. Between 1980 and 2020, rates rose from less than 1 percent to 11.2 percent — a greater than tenfold increase.
Today, the countries with the highest rates of type 2 diabetes are Pakistan, French Polynesia, and Kuwait.
Type 2 diabetes was once unusual in children, but that, too, is changing. “Unfortunately, we’re seeing it in very young children now,” notes Fung.
Why are so many more people now at increased risk of developing metabolic dysfunction?
On an individual level, genetics can play a role. Those with a family history of type 2 diabetes are more likely to develop it. Research suggests several gene variants may contribute to increased risk, particularly those involved in the regulation of insulin production, insulin action, or glucose metabolism.
“In general, your risk is higher if you have a higher body mass index,” Fung says, “but many people with a normal BMI still develop diabetes.”
People of African, Hispanic or Latino, Native American, Asian, and Pacific Islander descent may be particularly susceptible to diabetes and metabolic dysfunction, even with a low BMI.
Still, heritable factors only account for so much. “The genetics of the human population have not changed in the past 20 years,” Fung says, yet disease prevalence has skyrocketed. “There’s clearly something environmental — whether it’s the foods we’re eating or the lifestyles we’re living —that’s increasing the risk for all of us.”
The Broader Context
There’s no doubt that diet and lifestyle are key contributors to the rising prevalence of type 2 diabetes. Smoking, sedentariness, sleep deprivation, chronic stress, and a nutrient-poor inflammatory diet have all been implicated.
Recent research suggests the health of your microbiome may even play a part. Certain gut bacteria produce inflammatory molecules that can increase insulin resistance. An imbalanced microbiome may host more of these kinds of microbes, as well as fewer beneficial bugs that produce short-chain fatty acids known to increase insulin sensitivity.
“The microbiome affects how you respond to carbohydrates,” Boham explains. “Some people will have a cup of beans and be perfectly fine, and for somebody else it will spike their blood sugar.” Differences in their microbiomes may be one of the reasons.
Environmental toxins are another likely contributor, including bisphenol A (BPA), a component of the plastic used for water bottles and found in the lining of some water-supply pipes. (It’s now rarely found in the lining of food cans after an effort to replace the chemical.) Studies show that Vietnam veterans exposed to Agent Orange have significantly higher insulin resistance compared with veterans who were unexposed.
Toxins may increase insulin resistance by harming mitochondria, the energy-producing parts of our cells, Boham says. “When mitochondria don’t work as well, then the whole process of keeping us insulin sensitive is damaged.” (Caring for your mitochondria is one of the best ways to take care of your health — and enjoy better energy, metabolism, and mental focus in the process. Here are seven ways to protect them.)
6 Strategies to Manage High Blood Sugar
Even though we can’t control all the risk factors for insulin resistance, there are still plenty of ways to improve our metabolic health. Consider these evidence-backed lifestyle tactics for preventing — and reversing — high blood sugar and insulin resistance. They can be used safely alongside prescription drugs that control blood sugar (such as Metformin and supplemental insulin) and may help reduce or eliminate the need for prescriptions over time.
1. Eat Balanced Meals
The simplest way to manage blood sugar is to consume less glucose. “If you eat a lot of glucose — and that’s not just sugary foods but starchy carbohydrates like bread, rice, and potatoes — then your blood glucose goes up,” Fung says.
The glycemic index (GI) ranks carbohydrates based on their impact on blood-sugar levels. Foods with a low GI tend to be absorbed more slowly, causing a more gradual, modest rise in glucose.
Still, the GI can only serve as a general guide because responses to glucose are highly individual. Genetics, the microbiome, body composition, and portion size all affect that response, which is why two people can have completely different reactions to the same food. (This is why a continuous glucose monitor can come in handy; more on that in a bit.)
Restrictive eating can lead to problems of its own, however, so rather than focusing exclusively on cutting down on carbohydrates, Weisenberger advocates for taking a broader view of a healthy diet. “Too often, people focus only on calories for weight, carbs for blood glucose, sodium for blood pressure, or fat for cholesterol,” she notes. “This myopic view of health and diet rarely leads to good outcomes.”
Make sure every meal contains combinations of different nutrients. This can naturally curb an over-emphasis on carbs.
Instead, emphasize variety. Make sure every meal contains combinations of different nutrients. This can naturally curb an over-emphasis on carbs. “Having a balanced meal tends to lead to better blood-sugar control than a carbohydrate-heavy meal without some protein or fiber,” Weisenberger says.
Protein is typically more filling than carbohydrates, so it can help reduce overeating and snacking. It also slows the absorption of carbohydrates, moderating their effect on blood sugar. Healthy fats (think nuts, seeds, avocados, and olive oil) produce a similar moderating effect on carbohydrates.
Fiber — both soluble and insoluble — is crucial here too. “Having a couple of foods at every meal with different types of fiber is going to be beneficial,” Weisenberger explains. “Some fibers slow down the release of glucose into the blood, and some are food for the good bacteria that produce helpful compounds that reduce insulin resistance.” (Wondering how much protein you actually need? Learn more about this macronutrient and how to get it from healthy sources.)
Finally, try eating your carbohydrates after some fiber, fat, and protein. “When you go to a restaurant, they start by bringing you bread, which is the worst thing to eat first,” Boham says. “Instead, start with salad with some olive oil. Starting with fiber, protein, and fat really helps with balancing blood sugar.”
2. Move More
When we exercise, we increase our body’s sensitivity to insulin, which decreases insulin resistance. And anything that decreases insulin resistance is going to help manage blood glucose.
Both cardio and strength training offer benefits here — and a combination of the two is best. “The increased insulin sensitivity following exercise could last for a couple of hours or a couple of days, depending on the duration and intensity of the exercise,” Weisenberger says.
Boham recommends two strength-training sessions and at least 150 minutes of cardiovascular exercise per week — and not all the cardio needs to be intense. “Going for a walk after you eat dinner is a wonderful activity that can help improve blood sugar after a meal,” she says.
The very act of exercising helps remove glucose from the blood, even if you’re insulin resistant.
Strength training helps build lean muscle mass, which is crucial for absorbing glucose. “The preferred place for blood sugar to go after eating is to the muscle, but if we don’t have a big muscle, we don’t have a big repository for that sugar to enter,” Weisenberger explains. (For more, see “Why Strength Training Is Essential.”)
She compares muscles to small and large buckets in a rainstorm — the big ones are going to hold a lot more rain. “That’s why we don’t want to lose muscle mass as we age; we want to build as much muscle as we possibly can.”
The very act of exercising helps remove glucose from the blood, even if you’re insulin resistant. “If you’re actively using your muscles, they don’t need those messages from insulin in order to take up sugar,” Weisenberger says.
Though longer bouts of exercise are most effective, simply moving around throughout the day also counts. Research shows that breaking up long periods of inactivity helps improve insulin sensitivity. The American Diabetes Association recommends three minutes of movement for every 30 minutes of extended sitting.
“That could just be walking to the bathroom, moving the laundry from the washer to the dryer, or getting up and doing some squats and stretches,” Weisenberger notes.
3. Try Time-Restricted Eating
Time-restricted eating (TRE) is a moderate form of intermittent fasting in which you eat only during a specific window of time each day. Usually that window is between four and 10 hours long. Studies indicate that TRE can lead to a reduction in fasting insulin levels, improved insulin sensitivity, and better glucose tolerance.
“If the underlying problem in prediabetes is too much glucose, you can either put less glucose into the system or let your body burn off the excess, which is what intermittent fasting does,” Fung says. “It’s the most powerful natural therapy for type 2 diabetes.”
Fung compares a body with too much glucose to an overflowing sink. “The strategy we have right now is that when the sink overflows, we get mops,” he says, referring to the medications used to manage type 2 diabetes. “But the best strategy is to turn off the tap and let the water drain out. Let your body burn off the glucose.”
During fasting, the body uses stored glucose, which is primarily glycogen from the liver, to meet its energy needs. As glycogen stores diminish, the body starts to burn fat for energy. This may help improve insulin sensitivity.
If you decide to try TRE, keep in mind that the body becomes more insulin resistant as the day goes on. “If you eat the same meal at noon or at 8 p.m., you’ll produce a higher amount of insulin after the later meal,” Boham notes. “[Eating] earlier is better when it comes to insulin resistance and prediabetes.” (To learn if you’re a good candidate for TRE, see “Everything You Need to Know About Intermittent Fasting.”)
4. Consider a Continuous Glucose Monitor
If you’re curious about your individual response to carbohydrates, a continuous glucose monitor (CGM) can be a useful tool. This device measures blood-sugar levels in real time with a sensor placed under the skin. A CGM may be prescribed by a doctor if you have type 1 or type 2 diabetes, but you can also find over-the-counter brands.
“CGMs give you information that you couldn’t get otherwise,” Fung says. “We know what the average response to any given food is, but we don’t know what your personal response is going to be. The CGM gives us personalized information about what foods are doing to us.”
A CGM may also offer insight into how sleep, stress, and meal timing are affecting your blood sugar, Boham adds. Still, she cautions that a CGM is best used for a short time, to avoid focusing too much on one kind of metric, and with the support of a provider who can help you interpret the information.
5. Reduce Inflammation
“Prediabetes is an inflammatory disorder,” Boham says, so training your focus on reducing inflammation can yield big benefits.
The simplest way to cool inflammation is by eating fewer inflammatory foods, especially hyperprocessed fare and known allergens like dairy and gluten. Increasing inflammation-fighting compounds from fresh, whole plant foods also helps. (Our bodies need inflammation to fight off infection, but too much of it for too long can spur a wide range of illnesses. Learning to manage it effectively is key. See “How Chronic Inflammation Affects Your Health” for a deep dive on this subject.)
“There’s been great research on phytonutrients and how they can help decrease inflammation after a meal,” Boham explains. “So, in addition to protein, fats, and fiber at each meal, think about including colorful plant foods. Just adding more spices to your meals can be really helpful.”
Regular relaxation also helps calm the system. “When we’re in a state of stress, our blood sugar goes up,” she says. “It makes sense. If you’re running from a tiger, the body wants more glucose in the blood so it can use it to run away.”
The reverse is true as well. “If we activate the parasympathetic, calming nervous system, we can actually bring down our blood sugar.”
Weisenberger adds that poor sleep is a type of physical stress on the body. “One night of poor sleep will increase insulin resistance even in healthy people. But if somebody habitually gets bad sleep, then we can see a big difference in insulin sensitivity.”
6. Experiment With Cold Therapy
A small body of research suggests that cold therapy — such as cryotherapy, polar plunges, ice baths, and cold showers — can lower fasting glucose and insulin levels and improve insulin sensitivity.
It may confer some of these benefits by creating what’s known as brown fat. “When we think of fat, we usually think of white fat, which stores calories. But there’s also brown fat,” Fung explains.
Brown fat stores energy in a smaller space than white fat; it also generates body heat and burns caloric energy.
Regular cold exposure helps generate more brown fat. “If it’s burning energy, that’s going to be useful in the treatment of prediabetes because it’s using up glucose,” Fung says, adding that more research is needed.
As always, the most sustainable way to manage your blood glucose is a personalized, holistic approach that suits your individual needs. If your A1C is running high, it’s worth the time to learn what works for you. Building supportive diet and lifestyle habits can mean the difference between managing a progressive metabolic disease or turning the tide for good.
Exploring Semaglutide for Diabetes Management and Weight Loss
Various drugs have long been used to help manage diabetes, including the commonly prescribed Metformin. In 2017, the U.S. Food and Drug Administration approved a semaglutide drug — part of a class of medications known as glucagon-like peptide 1 receptor agonists — with the brand name Ozempic for the treatment of type 2 diabetes.
Since then, semaglutide has also been approved for weight management under the brand name Wegovy. These injectable medications lower blood-sugar levels, increase feelings of fullness, and delay the emptying of the stomach after eating.
“The major reason these drugs work is that they cause you to lose your appetite,” explains nephrologist Jason Fung, MD. “But if you don’t pair that with proper dietary habits, then it’s just a temporary fix because as soon as you stop taking the drug, all the changes reverse.”
“The major reason these drugs work is that they cause you to lose your appetite,” explains nephrologist Jason Fung, MD. “But if you don’t pair that with proper dietary habits, then it’s just a temporary fix because as soon as you stop taking the drug, all the changes reverse.”
A 2023 analysis of pharmacy claims found that two-thirds of people who were prescribed weight-loss drugs like Wegovy stopped taking them within one year. Cost may be a factor, especially for people paying out of pocket. Side effects are another. These can include nausea, vomiting, diarrhea, and, more rarely, stomach paralysis, bowel obstruction, and pancreatitis.
Fung notes that curbing your appetite may be a blessing in the short term, but it loses its appeal. “These drugs take away hunger, but they also take away the pleasure of eating. If you take that away for six months, people are happy because they’re losing weight and getting healthier. But take that enjoyment away for two, three years, and it leads to poor compliance. And when you stop taking it, the problems multiply.”
“The biggest concern with these medications is that we’re seeing too much loss of lean muscle mass,” explains functional-medicine physician Elizabeth Boham, MD, MS, RD. “Whenever you lose lean muscle mass, your metabolism decreases.” Studies show that lost muscle mass also contributes to frailty in older adults.
Furthermore, the weight people regain after stopping the medication generally comes back as fat instead of muscle.
A personalized risk–benefit analysis may come out in favor of semaglutide for some people facing certain or extreme health challenges. “If it helps someone not have gastric bypass surgery, there may be a net benefit,” Boham says. Regardless, anyone who opts to take semaglutide will benefit from working with a personal trainer to minimize loss of lean muscle mass.
