Does obesity cause diabetes?

Diabetes and obesity are two health conditions affecting many people worldwide, making it one of the most significant public health issues. They’re also becoming more common, with some experts predicting a sixfold increase in the number of adults with obesity in 40 years. As for obesity, the World Health Organization estimates that the condition affects seven times more people today than it did 40 years ago. Today, around one in ten Americans have diabetes. If you’re interested in how obesity and diabetes relate, read on. We explain the connection between the two conditions, and what you can do to manage and (even reverse) your risk of developing type 2 diabetes.

Generally, yes. While you can develop diabetes without being obese, obesity significantly raises your risk of type 2 diabetes mellitus. In fact, most people with type 2 diabetes have obesity or high body fat, especially in their abdominal area. 

It is important to note that obesity is associated with type 2 diabetes, but not with type 1 diabetes. Type 2 diabetes is characterized by high blood sugar levels (hyperglycemia) caused by a diminished insulin response (the body becomes “resistant” to insulin), while type 1 diabetes describes a lack of insulin altogether. Type 2 diabetes is much more common, affecting about 90% of people with diabetes.

Technically, obesity describes a condition of excess body fat. It may be diagnosed when a person has a body mass index (BMI) of 30 or higher, although the BMI isn’t a perfect measure.

“Diabesity” is a portmanteau that describes the negative health effects of having both obesity and type 2 diabetes. It is not an official medical term or diagnosis, but the fact that health experts came up with this word shows how closely the two conditions are linked. 

Having both conditions increases your risk of certain health conditions, especially those affecting the heart (cardiovascular disease), but obesity and type 2 diabetes also each pose health risks of their own. The chronic high blood sugar and metabolic changes brought on by type 2 diabetes can damage other organ systems in your body. Obesity carries its own health risks, including high blood pressure, high cholesterol, heart failure, heart disease, and premature death. 

Having diabesity increases your cardiovascular risk, as well as your risk of stroke and cancer, including liver, pancreatic, endometrial, colorectal, and postmenopausal breast cancer.

Obesity can cause and worsen diabetes. There is a direct relationship between body size and diabetes risk. As your BMI grows, so does your risk of type 2 diabetes. 

When the pancreas operates normally, it uses insulin to move glucose out of your blood and into your muscles for energy, or into your liver for storage. In type 2 diabetes, this process doesn’t work properly. People with type 2 diabetes have insulin resistance, so it’s tougher for glucose to enter the body’s muscles and tissues. Obesity is a triggering factor for that process: to put it simply, fat tissue is believed to lead to inflammation that leads to insulin resistance. 

As a result, their pancreas has to work harder and produce even more insulin to do the same job. Over time, the pancreas gets so overworked that it becomes unable to release enough insulin to level out blood glucose levels, leading to type 2 diabetes.

No. People who have obesity are more likely to develop type 2 diabetes. But not everyone who has obesity will get diabetes. Your likelihood of developing type 2 diabetes also depends on other factors, including your diet, exercise routine, stress levels, family history, and other health conditions, such as hypertension, heart disease, or PCOS for women.

• Lifestyle: A lack of exercise and physical activity can raise your risk of both obesity and diabetes. Poor sleep may be a risk factor for both obesity and diabetes. Smoking can affect your metabolism and is associated with an increased risk of diabetes and obesity.

• Diet: Eating a high-calorie diet — especially one with lots of sugar, fat, processed meats, and refined grains — is associated with an increased risk of developing type 2 diabetes. It can also lead to weight gain and obesity.

• Genetics: Your genes can play a role in developing obesity and diabetes. Certain ethnic groups have an increased risk of both obesity and diabetes, including African Americans, Hispanics, Native Americans, Asian Americans and Pacific Islanders.

• Age: As you age, your risk of both obesity and diabetes increases. While about 10% of all Americans have diabetes, around 25% of those over age 65 do.

For people who are obese and overweight, weight loss is often one of the first steps to treating and managing type 2 diabetes. By losing weight, you can improve your blood sugar control, and you may even be able to reduce the medications you take to control your diabetes. 

In addition to controlling type 2 diabetes, people with obesity who lose weight experience other benefits, such as improved sexual and physical functioning, and quality of life. Losing 5% of your body weight can improve blood sugar levels, reduce your need for medication, and improve your quality of life, while losing more than 10% can lower the risk of heart problems. Some research suggests switching to a very low-calorie diet can send diabetes into remission for up to two years in people with both type 2 diabetes and obesity, but these diets are not for everyone. 

Often, health professionals recommend starting with simple lifestyle changes like a reduced-calorie diet and exercise, but sometimes, those changes aren’t enough to bring blood sugars under control. In those cases, medications and metabolic surgery can help. For example, glucagon-like peptide 1 (GLP-1) receptor agonists like semaglutide (brand names Ozempic, Wegovy) can help with blood sugar control and weight loss. 

Health professionals use two blood tests to diagnose type 2 diabetes. The tests include:

• Glycated hemoglobin (A1C): Diabetes is usually diagnosed with this test. It can be done on the spot (no fasting required!) and offers an estimate of your average blood glucose levels over the last 2–3 months. A test result of 6.5% or higher is diagnosed as diabetes.

• Fasting plasma glucose: For this test, you’ll fast for at least eight hours overnight (no eating or drinking) prior to providing a blood sample. A fasting plasma glucose (FPG) result of 126 mg/dL or higher is diagnosed as diabetes.

Being overweight or obese can increase your risk of prediabetes and type 2 diabetes. But the development and progression of diabetes can be prevented, postponed, or even reversed if you take action to get your blood glucose within a normal range. According to the Centers for Disease Control and Prevention (CDC), losing 5-7% of one’s body weight and adding 150 minutes of exercise per week can cut the risk of developing type 2 diabetes by up to 58%. 

Diet, lifestyle changes, medications, and surgery can all be effective weight loss strategies. 

Diet

Making healthier food choices can help you achieve a healthy weight. Start by limiting or avoiding fatty and sugary foods, especially saturated fats, refined carbohydrates, and high fructose corn syrup.

Instead, follow a high-fiber diet. Research suggests that plant-based diets in particular, such as the Mediterranean diet, vegetarian diet, or DASH diet, can reduce your risk of type 2 diabetes. 

Certain eating behaviors may be linked to diabetes, according to a small amount of evidence. For instance, skipping breakfast and snacking are associated with an elevated risk of diabetes, while eating a regular breakfast and avoiding snacks may lower your risk. 

Lifestyle changes

Find ways to lower your stress, like exercise. For people with diabetes, experts recommend aerobic exercise for 90 to 150 minutes per week. In the long term, exercising for at least 200 to 300 minutes per week can help with weight loss.

Stop smoking and drinking. Smoking is linked to diabetes, but it changes your body composition in ways that can affect weight. And, despite being associated with a drop in body weight, heavy smokers are nearly twice as likely to have abdominal fat as never-smokers. While some weight gain can be expected when you stop smoking, some studies have found that obese individuals may actually lose a small amount of weight.

Bariatric surgery

The best way to prevent diabetes if you are obese is to lose a lot of weight, and, if you’re a candidate, bariatric surgery can help you do that quickly. Surgery may be recommended for people with a BMI of at least 35, depending on their health situation.

Bariatric surgery often relieves other conditions associated with diabetes and obesity as well, such as obstructive sleep apnea and hypertension. 

Medication

Medications, including GLP-1 receptor agonists like Ozempic, Wegovy, and Saxenda, can help control blood sugar levels, lower cardiovascular risk, and produce weight loss — a one-two-three punch for those hoping to stave off the progression of diabetes. These medications promote weight loss by telling your brain you’re full earlier, and slowing down digestion, reducing your appetite.

Diabetes can often be preventable. Start taking action today to lower your risk. Pick one of the ideas above, like limiting sugary foods, or talking to a healthcare professional about GLP-1s for weight loss. Every bit helps, and as you gain momentum, you can continue adopting other lifestyle changes to lower your risk.

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Current version

June 02, 2023

Written by

Amelia Willson

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.