It is not caused by eating too much sugar, per se, but it has everything to do with how your body handles the sugar you consume and what you do to manage the level of sugar in your blood.
Types and Prevalence of Diabetes Mellitus, Defined
A number of disorders are grouped under the umbrella of diabetes, usually identified by type. Each type is distinct in terms of what causes it, how it's treated, and the complications that can arise.
Here's a quick look at each type of diabetes: definitions, some fast facts, and how common each type is in the United States and worldwide.
Diabetes 101: What Are the Different Types of Diabetes?
Prediabetes and Insulin Resistance
Prediabetes is a condition that can lead to type 2 diabetes. To understand what causes it, you have to understand how the body handles glucose and processes it into energy.
Type 2 Diabetes
Type 1 Diabetes
Type 1 diabetes is an autoimmune disorder in which a person’s own immune system attacks and destroys the beta cells in the pancreas that make insulin. Without that hormone, hyperglycemia develops. People who have type 1 diabetes must take insulin injections to replace the insulin their body doesn’t make, as well as monitor their blood glucose level daily.
Complications of type 1 diabetes are similar to those found in type 2 because in both cases, chronically elevated blood sugar causes long-term damage. But people with type 1 are especially vulnerable to developing a potentially life-threatening condition known as diabetic ketoacidosis (DKA). When the body doesn’t have enough insulin to convert glucose into energy, it begins to break down fat for fuel. The result is a buildup of acids in the bloodstream known as ketones.
“We typically tell patients that if your blood sugar is above 250 mg/dL [milligrams per deciliter], you want to test your urine for the presence of ketones — or check if you are going to exercise and your blood sugar is above 300 mg/dL. It can be life-threatening, because high levels of ketones in your blood can actually make your blood too acidic,” says Jordana Turkel, RD, CDCES, of Park Avenue Endocrinology and Nutrition in New York City.
Type 1.5 Diabetes
“When you have a patient who is over the age of 30 and they come in with classic symptoms — the blood sugar is pretty high — if you give them metformin, they may be able to still manage some of their symptoms. But within the next five years, those beta cells that are producing the insulin are going to stop working, and then they are going to turn into a true type 1 patient requiring insulin,” says Turkel.
Type 3 Diabetes
Signs and Symptoms of Diabetes
If you suspect that you have prediabetes or diabetes because of any of the symptoms below, you'll want to visit your healthcare provider immediately.
How Is Diabetes Diagnosed?
To be tested for prediabetes or any type of diabetes, you'll need to visit your healthcare provider's office. Unfortunately, you cannot test for the disease at home. As a first step in diagnosing you, the healthcare provider will take a medical history, including information about anyone else in your family who has had diabetes and what type. Next, they will likely order some of these lab tests to measure your blood glucose.
Fasting Plasma Glucose Test
This test is performed after you’ve had nothing to eat and no more than small sips of water for eight hours. Here’s what the results mean:
- Normal is less than 100 mg/dL.
- Prediabetes is 100 to 125 mg/dL.
- Diabetes is 126 mg/dL or higher.
Hemoglobin A1C Test
- Normal is less than 5.7 percent.
- Prediabetes is 5.7 to 6.4 percent.
- Diabetes is 6.5 percent or higher.
Oral Glucose Tolerance Test (OGTT)
- Normal is less than 140 mg/dL.
- Prediabetes is 140 to 199 mg/dL.
- Diabetes is 200 mg/dL or higher.
Random Plasma Glucose Test
This test for diabetes doesn’t require fasting beforehand, and while it can suggest diabetes with results of 200 mg/dL or higher, it is not typically used.
- Autoantibody Tests These are most often done to test for type 1 diabetes or LADA. Common tests look for antibodies targeting insulin or certain pancreatic cells.
- C-Peptide Test This measures a protein that mirrors the level of insulin in the body. Low levels can indicate type 1 diabetes or LADA.
- Genetic Testing for Monogenic Forms of Diabetes Maturity-onset diabetes of the young and neonatal diabetes mellitus may be detected.
Causes and Risk Factors of Diabetes
You can take steps to lower your chance of developing types of diabetes that involve insulin resistance, such as prediabetes, type 2 diabetes, or gestational diabetes. (Type 1 diabetes isn’t known to be preventable.)
Diabetes Risk Factors You Can Help Control
Some of the strongest risk factors for developing insulin resistance are under your control:
- Excess weight, especially a body mass index of 25 or higher for people in most ethnic groups in the United States; 23 or higher for Asian Americans; and 26 or higher for Pacific Islanders
- A diet that is high in fat, added sugar, and refined carbohydrates
- No regular exercise
- Tobacco smoking
Diabetes Risk Factors You Can’t Control
- Age 45 or older
- A family history of diabetes
- Alaska Native, American Indian, Asian American, Black, Hispanic or Latino, Native Hawaiian, or Pacific Islander ethnicity
- A history of gestational diabetes or a child with a birth weight of 9 pounds or more
- Polycystic ovary syndrome (PCOS)
People should know that they can do things to lower their risk of developing the insulin-resistant forms of diabetes, but they should not feel guilty if they develop the disease anyway, says Joshua D. Miller, MD, the medical director of diabetes care at Stony Brook Medicine in New York, who manages type 1 diabetes himself.
“No one wakes up and says they want to develop diabetes, whether it be type 1 or type 2. Developing diabetes is completely out of most people’s control — even along the type 2 diabetes spectrum where lifestyle and obesity play a larger role in developing the disease,” Dr. Miller says. “Working past the notion that you’ve done something wrong because your blood sugar is too high is probably the most important challenge to overcome in order to help people become better at managing their disease.”
Is Diabetes Hereditary? The Role of Genetics in Risk
While your risk score won’t predict with 100 percent certainty whether you’ll develop a polygenic form of diabetes, it may help you focus on taking preventive measures, says Mónica Alvarado, a certified and licensed genetic counselor and the regional administrator for genetic services at Kaiser Permanente in Pasadena, California. “The advantage of that is that someone might be more motivated to control their diet and exercise, and to monitor their glucose and hemoglobin A1C more regularly, than if they just have information that their risk for diabetes is higher than that of the average person,” she says.
Alvarado also says that the influence of family history is complex, and it’s hard to know whether relatives are sharing genetic variations alone or also sharing a diet, lifestyle, and environment that make them more prone to developing diabetes.
Treatment and Medication Options for Diabetes
If you’ve been diagnosed with diabetes, your treatment regimen will vary based on your individual health and the type of diabetes you’re managing. But one treatment that's often closely linked with the condition is insulin.
There are a few types of insulin to get you through the day.
Basal, or Long-Acting, Insulin This form begins to work several hours after injection and keeps working steadily over a 24-hour period without any peak effect. It's always in the background regardless of what or when you eat. “It’s what the pancreas would be dripping into the system constantly,” says Grace Derocha, RD, CDCES, of Blue Cross Blue Shield of Michigan in Detroit. Examples include levemir (Detemir), degludec (Tresiba), and glargine (Lantus, Toujeo, and Basaglar).
Intermediate-Acting Insulin Isophane (Humulin N), Novolin N, and lente (Lente) are slowly released into the bloodstream so they can last up to 24 hours. If someone is on a pump, the amount is adjusted slightly depending on the level of activity or whether someone is awake or asleep, says Derocha.
Instead of or in addition to insulin, a number of oral medications are used to treat diabetes, particularly in people whose bodies still make some insulin and whose A1C is below 9.
Thiazolidinediones The only approved drug in this class is pioglitazone (Actos), which makes the body more sensitive to the effects of insulin.
DPP-4 Inhibitors Sitagliptin (Januvia), linagliptin (Tradjenta), saxagliptin (Ongliza), and aloglipitin belong to this class. These drugs improve the level of insulin made after a meal and help lower the amount of glucose made by the body.
GLP-1 Receptor Agonists Liraglutide (Victoza), dulaglutide (Trulicity), and Ozempic (semaglutide) belong to this class of drugs, which mimic the effects of the incretin hormone GLP-1, which is excreted during a meal and lowers blood sugar.
GLP-1 Receptor and GIP Agonists There is currently one drug available in this class, tirzepatide (Mounjaro), which the U.S. Food and Drug Administration approved in May 2022. Studies suggest tirzepatide helps lower A1C and manage hunger, in some cases leading to significant weight loss.
There are also continuous glucose monitors that you wear on your arm or abdomen for 10 to 14 days, including Freestlye Libre, Dexcom G6, and Medtronic Guardian.
Diet and Lifestyle Tips to Help Keep Blood Sugar in Check
Depending on the type of diabetes you're managing, you'll need to work with your healthcare team to devise a diet and lifestyle program that meets your individual needs. Then you'll need to build a support team in and outside of the home to help you stay on track.
Focus on Quality Food
Become a Carb-Counting Pro
“We try to teach carb control, carb consistency, and carb counting,” says Derocha. “I call it the ‘three carbohydrate C's’ that are important for any type of diabetes and blood sugar control.” In short: Counting your carbohydrates and keeping them at a consistent level for every meal can help you to stabilize and control your blood sugar.
Consider Glycemic Index and Glycemic Load
Some people also look at how various foods containing carbohydrates are likely to raise their blood sugar, according to the food's rank on the glycemic index (GI) and its glycemic load (GL).
The GI is a measure of how food raises blood glucose levels. Foods are ranked on a scale of 0 to 100, with 100 being pure glucose. Low-GI foods rank at 55 or less (such as oatmeal, sweet potatoes, and most fruit); medium-GI foods rank 56 to 69 (brown rice and corn); and high-GI foods (think bagels, popcorn, and melon) rank 70 and above.
“A high-glycemic-index food will raise blood sugar more than a food on the medium or low end of the spectrum,” explains Derocha, noting that “the glycemic load itself is really a better way to tell you how that particular food will then affect your blood sugar.” This is because GL compares the ability of the same amount of carbs in each food to raise your blood sugar higher.
To figure out a food’s glycemic load, multiply its GI by the number of carbohydrate grams in a serving, then divide that by 100.
Knowing a food’s specific GL can help you lower and control your blood sugar, but Derocha stresses that it’s most effective to use this strategy in concert with carb counting and healthy eating.
Explore the Ketogenic Diet and Diabetes
Some people with type 2 diabetes go on a ketogenic, or keto, diet diet; this high-fat, low-carb regimen forces your body to burn fat instead of carbs for fuel. Because the approach is so low in carbohydrates, the body quickly depletes its store of glucose and then enters a natural state of ketosis, in which fat is broken down by the liver into acids known as ketones, which become the main source of fuel. “For type 2 patients on medication or who have PCOS with insulin resistance, a version of the ketogenic diet can help,” says Turkel, particularly if losing weight is a goal.
But, she adds, people who have insulin resistance are typically trying to manage a lot of diet and lifestyle changes at once to help control their blood sugar, so she doesn’t recommend the rigors of a ketogenic diet as a long-term solution. Additionally, if you are taking oral diabetes medications, you may be at risk of potentially serious complications, like hypoglycemia.
Eat a Diabetes-Friendly Diet When Managing Gestational Diabetes
Based on her personal experience with gestational diabetes, Derocha says that it’s manageable. “During my pregnancies, I did not have to take any medication, and I did not take any insulin, because I was able to control it with my diet and lifestyle changes,” she says.
Don't Discount the Importance of Exercise
As for what you should do for exercise, Dr. Happel suggests finding an activity you like and sticking with it. “Make it fun, make it something you enjoy doing,” she says. “Do it with family, do it at work. If you like to dance, then dance. Walking, working in the garden — just be active.”
Complications of Diabetes
Poorly managed blood sugar can lead to serious and even life-threatening health complications, regardless of the type of diabetes you have. But there are some specific health risks by type that you should be aware of.
Type 1 and Type 2 Diabetes
A number of complications can arise from types 1 and 2 diabetes if they’re uncontrolled or poorly controlled for a long period of time:
- Damage to blood vessels, resulting in heart disease, stroke, and kidney disease
- Blindness, including diabetic retinopathy, diabetic macular edema, cataracts, and glaucoma caused by swelling, nerve damage, or damage to the tiny blood vessels in the eye
- Bladder problems and sexual dysfunction, also due to damage to blood vessels or nerves
- Orthostatic hypotension, a drop in blood pressure upon standing up caused by nerve damage
- Slow-healing wounds, as a result of blood vessel damage
- Diabetic ketoacidosis, a buildup of acids in the bloodstream known as ketones, occurring when the body doesn’t have enough glucose to use as fuel.
Other Possible Complications of Diabetes
Numerous complications are associated with diabetes mellitus.
Diabetic Neuropathy Nerve damage affects nearly 60 percent of people with diabetes. Distal symmetric polyneuropathy is the most prevalent within that group. With this form of neuropathy, the most distant nerve fibers from the central nervous system malfunction first. “It usually starts in the feet. [You’ll] feel tingling or numbness at the bottom of the feet, and then [it] may slowly progress upward in the foot to the ankle and the legs,” says Happel.
The pattern is usually symmetrical, affecting limbs on both sides. Sometimes a burning sensation takes hold, which Happel says is sometimes mistaken by patients for athlete’s foot. Eventually, numbness and then profound loss of sensation can set in, along with the loss of reflexes.
Symptoms of hypoglycemia include jitteriness or shakiness, blurred vision, fatigue, dizziness, disorientation, a fast or irregular heartbeat, irritability, weakness, or extreme hunger. Severely low blood sugar may result in unconsciousness and seizures.
Happel says that one reason why people end up with HHNS is noncompliance with their insulin treatment regimen, especially among teens and college students with type 1 diabetes. “They don’t want to be different from their friends, so they don’t take their insulin. Then they go out and have some drinks. Alcohol, when it is broken down in the body, is also broken down into sugars. But they are not taking their insulin, and they wind up in the hospital,” Happel explains.
But people with any type of diabetes are at risk for this complication, especially if they’re insulin-dependent. Noncompliance isn’t the only trigger, either; sometimes a person who develops HHNS is fighting another illness that has weakened and dehydrated them, says Happel.
Treatment generally happens in the ICU. “One of the first things is fluid resuscitation. They are 4 to 6 liters of fluid behind by the time they develop these complications,” says Happel. Insulin is administered, and electrolyte balances are also addressed. The best way to avoid HHNS is to monitor your blood sugar, take any insulin or medications you are prescribed in the proper dosage, and stick to your diet and exercise plan to manage diabetes.
Gestational Diabetes Complications
Is It Possible to Reverse Diabetes? Answers to FAQs Like This
Short answer: Maybe. Get more details on that common question and others below.
Q: How do I know if I have diabetes?
Q: Does sugar cause diabetes?
A: Not really, but diabetes has everything to do with how your body handles the sugar you consume. Diabetes mellitus is a group of metabolic disorders that cause the level of glucose (sugar) in your blood to be too high. This is called hyperglycemia.
Q: Which is worse: type 1 diabetes or type 2 diabetes?
Q: Is type 2 diabetes genetic? What about type 1 diabetes?
Nonetheless, risk scoring cannot tell you with certainty if you will develop one of the disorders. Family history is another risk factor, but it’s hard to know whether that is due to sharing genetic variations with relatives or to also having a diet, lifestyle, and environment in common.
Q: What does prediabetic mean?
Q: Can people with diabetes donate blood?
Taking oral medications and most forms of insulin to maintain that control is okay, but if you have ever used bovine (beef) insulin made from cattle from the United Kingdom since 1980, you are ineligible, because of a concern about Creutzfeldt-Jakob disease, also known as “mad cow disease.” If you're in doubt about your blood sugar level or what insulin you have taken, check with your doctor.
Q: Can people with diabetes eat fruit?
“At one given time you don’t want to have more than 1 cup of cut fruit or a cup of berries or one small piece of fruit,” Turkel advises. “And you never want to eat a piece of fruit or cup of fruit without a protein or a fat.” Adding protein or fat slows down the impact of the fruit’s sugar in your bloodstream and lessens the chance of a spike in blood sugar. “If you like fruit, pair it with some protein — a handful of nuts, a hard-boiled egg — and be strategic about it. And limit it to only twice a day.”
Q: What is a diabetic diet?
Q: What foods should people with diabetes avoid?
Q: Can people with diabetes get tattoos?
A: Yes, but you should check with your doctor first, and be sure of a few things, says Derocha: “Obviously you would not do this if you were pregnant [and have gestational diabetes], but with type 1 or type 2, you’d really have to have good blood sugar control. That is because one of the side effects of poor sugar control is an inability to heal [well] and to fight off infection.”
Q: What is diabetes insipidus?
Q: What does diabetic nerve pain feel like?
Q: Can dogs get diabetes?
Q: Can you die of diabetes?
Q: Can diabetes cause low blood sugar?
Signs that your blood sugar has dropped can include feeling shaky or jittery; having blurred vision, fatigue, dizziness, disorientation, or fast or irregular heartbeat; being irritable; and feeling weak or extremely hungry. If left untreated, hypoglycemia can result in unconsciousness and seizures.
If you have diabetes, check your blood glucose if you notice any of these symptoms, and if your number drops below 70 mg/dL (or the target you’ve set with your doctor), take in 15 grams of carbohydrates right away, then check your blood glucose 15 minutes later. Repeat this until your blood glucose is on target. This is called the rule of 15s. If it doesn’t help you meet your target after several attempts, use oral glucose.
Q: Can diabetes be reversed?
Additional reporting by Moira Lawler.
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