Hidden Dangers of Undiagnosed Diabetes

Diabetes and cardiovascular disease must be good buddies because they like to hang out together...

  • At least 68 percent of people age 65 or older with diabetes die from some form of heart disease; and 16 percent die of stroke.
  • Adults with diabetes are two to four times more likely to die from heart disease than adults without diabetes.
  • The American Heart Association considers diabetes to be one of the seven major controllable risk factors for cardiovascular disease.

The good news is that diabetes is easily diagnosed and can be controlled, and those consequences can be reduced. The bad news is there is a lot of undiagnosed diabetes: According to the AHA, there are 7.6 million adults with undiagnosed diabetes in the United States, and a further 81.6 million adults with prediabetes.

Endocrinologist, Dr. James Dudl

We asked endocrinologist James Dudl, diabetes lead at Kaiser Permanente’s Care Management Institute, how it could be that a disease so common and potentially harmful could be so greatly undiagnosed. “Diabetes usually progresses over a seven- to 10-year period before the sugar is so high it can be felt by noticing its symptoms like weight loss, thirst, frequency of urination or blurred vision,” Dudl said. “However, it can be detected by a blood test, and those consequences avoided.”

Types of Diabetes

Diabetes is a condition that results in blood sugar rising to dangerous levels. Blood sugar, also called glucose, is regulated by insulin, a hormone produced in the pancreas. Glucose in our bodies is what provides energy to our cells. With the help of insulin, cells throughout the body absorb glucose and use it for energy.

Diabetes is designated as type 1 or type 2. In type 1, insulin production is destroyed, which means all people with type 1 need to take insulin to make up for what their body isn’t making. Type 2 occurs when the body does not produce enough insulin or resists its own insulin, and pills or more insulin both can help.

“It is possible for sugar to build to very high levels in the blood — A1c of 8 for example — and stay elevated for two or more years, and it may not create symptoms,” Dudl said. “Eventually the excess comes out in the urine, but by that time the damage is already done. This is called a legacy effect, bad sugar control early results in complications years later. In two landmark studies, it was shown there were significant increases in blindness, amputations and renal failure, what we call microvascular complications, and macrovascular problems like heart attack and stroke.”

As an example, if blood sugar goes over 180 (A1c of 8) at age 40 then returns to normal, at 47 the person has an increased risk of eye, nerve and kidney damage. “If the A1c is over 8, the risk is even higher, and over 9 it’s even more, even if it comes back to normal,” Dudl said. “Of course, if the A1c is over 10 or 12, it’s much faster and more severe.”

So, if the damage is accumulating, does any amount of excess glucose harm the cells — for instance, if you eat a high-sugar dessert, does it impact you? Dudl explains it this way: “Elevated glucose damage is accumulated over time, often 10 years or more. It does have an effect each minute it’s high, but it is very small, like 1/10,000 of the minutes it will take to go blind, for instance,” he said. “So, there is no effect that causes big damage in a few minutes but accumulated over a year it does — there will be more drop in vision, or some nerve pain, or some loss of kidney function.”

Risk Factors

Diabetes risk factors are not uncommon. According to the Centers for Disease Control and Prevention, you’re at risk for developing type 2 diabetes if you:

  • Have prediabetes
  • Are overweight
  • Are 45 years or older
  • Have a parent, brother, or sister with type 2 diabetes
  • Are physically active less than three times a week
  • Have ever had gestational diabetes (diabetes during pregnancy) or given birth to a baby who weighed more than 9 pounds
  • Are African-American, Hispanic/Latino American, American Indian, or Alaska Native (some Pacific Islanders and Asian-Americans are also at higher risk).

For adults without symptoms of diabetes or other risk factors, the American Diabetes Association advises testing the blood sugar or A1c at age 45 and, if results are normal, to be tested at least every three years after that. If you are overweight or obese and have any of the risk factors mentioned above, or have any of the following, you should be tested regardless of age:

  • Immediate relative with diabetes
  • History of cardiovascular disease
  • High blood pressure
  • HDL cholesterol level under 35 mg/dL and/or triglyceride level above 250 mg/dL
  • Women with polycystic ovary syndrome
  • Physical inactivity
  • Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis, nigricans)

Women who’ve been diagnosed with gestational diabetes should be tested at least every three years and those with prediabetes should be tested yearly.

To better understand your risk, take the American Diabetes Association Type 2 Diabetes Risk Test.

The Consequences

“In general, high blood sugar can lead to blindness, amputations, and kidney disease,” Dudl said. “Frequently associated high blood pressure, elevated cholesterol and some vessel damage can lead to heart attacks and strokes. Hypertension also may lead to kidney disease and many of these complications add even more risk on each other.”

The kind of damage experienced somewhat depends on how old a person is when it starts. “In younger people, vision problems, foot insensitivity that leads to ulcers and kidney disease come first. In older people, heart attacks and strokes come more quickly, which may lead to diabetes first being discovered,” Dudl said.

In addition to those complications, the American Diabetes Association lists:

Skin complications that include bacterial infections, fungal infections and itching. They get common skin conditions more easily.

HHNS (Hyperosmolar Hyperglycemic Nonketotic Syndrome) is a serious condition most frequently seen in older persons and is usually brought on by an illness or infection, sometimes uncontrolled blood sugar and can result in severe dehydration.

Gastroparesis is a disorder in which the stomach takes too long to empty its contents because of damage to the vagus nerve, which controls the movement of food through the digestive tract.

Diabetes affects men and women similarly: 11.4 million men and 12 million women have diagnosed diabetes; 4.5 million men and 3.1 million women have undiagnosed diabetes; 46.2 million men and 35.4 million women have prediabetes. Before menopause, women have lower rates of cardiovascular disease, but researchers have found that advantage disappears in premenopausal women with diabetes. Cardiovascular disease is the leading cause of death and hospitalization in people with type 2 diabetes.


Prediabetes means that your fasting blood sugar levels are higher than normal (between 100 mg/dl and 125 mg/dl), but not to the levels of diagnosed diabetes (126 mg/dl and above). People with prediabetes have a higher risk of developing type 2. People with prediabetes are more likely to develop diabetes, and they are more likely to have a heart attack or stroke.

Remember the millions of Americans with undiagnosed diabetes? This may be one of the reasons: Prediabetes has no distinct symptoms. None. So, it’s necessary to be tested regularly if you have any of the risk factors listed above. Dudl says that prediabetes does not always lead to diabetes, “but progression over time is the rule.”

Here’s some good news — you can reduce your risk by changing your diet, losing weight and getting physically active. And if you smoke, quit. “Weight loss and exercise are always beneficial in type 2 diabetes and can delay the onset of diabetes, but they cannot reverse the underlying process, so if being overweight returns, the diabetes will too,” Dudl said. “And diet and exercise can definitely limit the medications needed. Diet and exercise can be tried for six months, but if there is insufficient change, then the drug metformin has been proven beneficial to preventing problems for over 10 years.”

Here’s the take away, get yourself and those you love tested. Start with the ADA online test — it’s just a few questions. If it shows you are at risk, ask your doctor to be tested, and then make that an annual event. “All the complications are preventable,” Dudl said, “and the treatments are safe.”

Learn how to make better eating choices for steady energy all day long.


This information is provided as a resource to our readers. The tips, products or resources listed or linked to have not been reviewed or endorsed by the American Stroke Association.

Edit ModuleShow Tags

AD. American Heart Association logo. Know your blood pressure numbers. And what they mean. Gain Control. button: learn more.


AD: American Heart Association logo. American Diabetes Association logo. Know diabetes by heart logo. Living with diabetes? Inspire others. Submit story button.


AD. American Heart Association Support Network. Everyone's diagnosis story is different and sharing yours can help others. Join the Support Network and share your experience. heart.org/SupportNetwork


AD: American Heart Association logo. Symptoms. Always feeling tired isn't normal. Learn the signs of Heart Valve Disease.


AD. American Heart Association logo. Know your blood pressure numbers. And what they mean. Gain Control. button: learn more.


Edit ModuleShow Tags

Special Topic Supplements

Edit ModuleShow Tags


Heart News

Heart health news you can use about new scientific findings, public policy, programs and resources.


Articles, poems and art submitted by heart disease survivors and their loved ones.

Life's Simple 7

Improving your health is as easy as minding seven simple health factors and behaviors. Tips and information to help you improve your health and enhance your quality of life.

Life Is Why

Everyone has a reason to live a longer, healthier life. These heart patients, their loved ones and others share their 'whys'. We'd love for you to share yours, too!

Simple Cooking

Cooking at home can be a daunting task, but a rewarding one for your diet and lifestyle (and your wallet). Making small changes in your diet is important to your heart health. Here are simple, healthy and affordable recipes and cooking tips.