Diabetes Complications: Short-Term Risks, Long-Term Effects, and Prevention

When I speak with patients about diabetes complications, I do not want them to think that complications are inevitable. Some risks can be reduced substantially, and many problems can be detected earlier through regular diabetes care.

Blood glucose is important, but it is not the only factor. Blood pressure, cholesterol, kidney health, smoking, body weight, physical activity, medication choice, access to care and other medical conditions can also influence complication risk.

Short-Term vs Long-Term Diabetes Complications

Why Diabetes Can Lead to Complications

Long-term exposure to high blood glucose can damage blood vessels and nerves. Over time, this may affect organs such as the heart, kidneys, eyes, brain, feet and digestive system.

However, glucose is only part of the picture. High blood pressure, abnormal cholesterol, smoking, kidney disease, excess body weight and other cardiovascular and metabolic risk factors can also contribute.

Short-term emergencies work differently. Severe hypoglycemia can temporarily deprive the brain of adequate glucose, while DKA and HHS are acute metabolic emergencies involving insulin deficiency, dehydration, ketones, electrolyte disturbances or very high blood glucose.

Short-Term Diabetes Complications

1. Low Blood Sugar (Hypoglycemia)

Hypoglycemia is especially important in people who use insulin or medicines such as sulfonylureas that can lower glucose too much.

• Level 1: glucose below 70 mg/dL (3.9 mmol/L) but at least 54 mg/dL (3.0 mmol/L).
• Level 2: glucose below 54 mg/dL (3.0 mmol/L).
• Level 3: severe hypoglycemia in which altered mental or physical function means the person needs assistance from someone else, regardless of the exact glucose value.

Symptoms may include shaking, sweating, hunger, fast heartbeat, dizziness, blurred vision, weakness, irritability, confusion or difficulty concentrating.

If the person is conscious and able to swallow safely, mild hypoglycemia is commonly treated with fast-acting carbohydrate followed by a glucose recheck according to the person's diabetes plan.

For a broader explanation of dangerous low and high readings, see what blood sugar level is dangerous .

2. Severe Hyperglycemia

Very high blood glucose can occur because of missed medication or insulin, infection, illness, dehydration, steroid treatment, insulin pump problems, major stress or newly diagnosed diabetes.

Warning symptoms may include extreme thirst, frequent urination, dry mouth, weakness, blurred vision and dehydration. The situation becomes more concerning when high glucose occurs together with vomiting, ketones, abdominal pain, confusion, unusual drowsiness or abnormal breathing.

A single high reading is not always an emergency. The glucose level needs to be interpreted together with symptoms, ketones, hydration, illness and response to the person's prescribed treatment plan.

Related guides: blood sugar between 250 and 400 mg/dL and blood sugar above 400 mg/dL .

3. Diabetic Ketoacidosis (DKA)

DKA develops when the body does not have enough effective insulin. The body begins breaking down fat for energy, producing ketones that can accumulate and make the blood acidic.

DKA is more common in type 1 diabetes but can also occur in type 2 diabetes. Triggers can include missed insulin, infection, acute illness, insulin pump failure, surgery or severe dehydration.

SGLT2 inhibitor medicines deserve special attention because DKA can occasionally occur with glucose levels that are lower than people expect. This is sometimes called euglycemic DKA. Symptoms and ketones therefore matter—not only the glucose number.

Warning signs include nausea or vomiting, abdominal pain, dehydration, ketones, fruity-smelling breath, deep or rapid breathing, severe weakness, unusual sleepiness or confusion.

DKA requires urgent medical assessment and should not be treated as an ordinary high glucose reading at home.

4. Hyperosmolar Hyperglycemic State (HHS)

HHS is another life-threatening hyperglycemic emergency. It occurs most often in people with type 2 diabetes and is particularly associated with very high glucose and severe dehydration.

HHS often develops more slowly than DKA. Possible warning signs include extreme thirst, frequent urination, very dry mouth, severe weakness, dehydration, increasing drowsiness, confusion, vision changes, seizures or loss of consciousness.

Suspected HHS usually requires emergency hospital care for fluid, electrolyte and glucose management and treatment of the underlying cause.

5. Diabetic Coma and Loss of Consciousness

Loss of consciousness associated with diabetes may result from severe hypoglycemia, DKA, HHS or another serious medical illness.

A person with diabetes who is unconscious, having a seizure, severely confused or unable to swallow safely needs emergency medical care. Do not put food, liquids or glucose products into the mouth of an unconscious person.

Long-Term Diabetes Complications

Long-term complications may begin before a person notices symptoms. This is why eye examinations, kidney tests, foot assessments and cardiovascular risk management remain important even when diabetes seems well controlled.

1. Heart Disease and Stroke

Diabetes increases the risk of cardiovascular disease, including heart attack, stroke, heart failure and peripheral artery disease.

Risk becomes particularly important when diabetes occurs together with high blood pressure, abnormal cholesterol, smoking, kidney disease or excess weight.

Cardiovascular prevention may include blood pressure treatment, cholesterol management, smoking cessation, physical activity, weight management and the use of diabetes medicines with proven cardiovascular benefit when clinically appropriate.

2. Diabetic Kidney Disease

Diabetes can damage the kidneys, often without causing symptoms during the early stages.

Two especially important tests are:

• urine albumin-to-creatinine ratio (UACR), which looks for abnormal albumin leakage into the urine; and
• estimated glomerular filtration rate (eGFR), which helps assess kidney filtration.

Later kidney disease may cause swelling, fatigue, appetite changes, foamy urine or shortness of breath, but patients should not wait for symptoms before being tested.

3. Diabetic Eye Disease

Diabetes can damage blood vessels in the retina, causing diabetic retinopathy. Diabetes is also associated with other eye problems, including cataracts and glaucoma.

Early diabetic retinopathy may cause no noticeable symptoms. More advanced disease may cause blurred vision, floaters, dark areas, difficulty seeing detail or vision loss.

Regular retinal or dilated eye examinations are therefore important, even when vision seems normal.

Seek urgent eye care for sudden vision loss, new flashes of light, a sudden increase in floaters or another rapid change in vision.

4. Diabetic Neuropathy

Diabetic neuropathy can affect sensory, motor and autonomic nerves. Peripheral neuropathy commonly begins in the feet and may cause burning, tingling, numbness, electric-shock-like pain or loss of sensation.

Some people have very few symptoms despite meaningful nerve damage. Reduced sensation increases the risk that blisters, cuts or burns will go unnoticed.

For more detail, see our guide to diabetic peripheral neuropathy and foot problems .

5. Foot Ulcers, Infection and Amputation Risk

Diabetes can affect both sensation and circulation in the feet. A seemingly minor cut, blister or pressure point can become serious if it is not noticed or if healing is impaired.

Warning signs include:

• a wound or ulcer;
• redness, warmth or swelling;
• pus, drainage or unpleasant odor;
• new numbness, tingling or burning;
• skin becoming blue, purple, black or unusually pale;
• a change in foot shape; or
• a wound that is not healing.

See diabetes foot symptoms and warning signs for a more detailed guide.

6. Gum Disease and Oral Health Problems

People with diabetes may be more prone to gum disease, tooth infection, dry mouth and oral fungal infections. Poor glucose control can also make some infections and dental problems harder to manage.

Brush regularly, clean between the teeth, attend dental checkups and tell your dentist that you have diabetes.

7. Skin Problems and Infections

Diabetes may increase the risk of dry skin, fungal infections, bacterial infections and slower wound healing, particularly when glucose is persistently high or circulation is impaired.

Spreading redness, pus, fever, red streaks, darkened tissue or a non-healing wound should be assessed promptly.

8. Digestive Problems and Gastroparesis

Diabetes-related autonomic nerve damage can affect digestion. Gastroparesis is one example in which stomach emptying becomes delayed.

Symptoms may include nausea, vomiting, early fullness, bloating, abdominal discomfort and unpredictable glucose rises after eating. These symptoms can have many other causes, so persistent problems should be medically evaluated rather than automatically attributed to diabetes.

9. Sexual and Bladder Problems

Diabetes can affect blood vessels and nerves involved in sexual and bladder function.

Men may experience erectile or ejaculatory difficulties. Women may experience vaginal dryness, discomfort or recurrent infections. Autonomic neuropathy may also contribute to urinary urgency, incomplete bladder emptying or incontinence.

These problems are common enough that patients should feel comfortable discussing them with a healthcare professional. Many causes are treatable.

Other Health Conditions Commonly Associated With Diabetes

Not every condition that occurs more often in people with diabetes should be described simply as a direct “complication.” Some are better understood as associated metabolic or health conditions that share important risk factors with diabetes.

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

MASLD is common in people with type 2 diabetes, obesity and insulin resistance. In some people it can progress from excess liver fat to inflammation, fibrosis and more advanced liver disease.

Depending on individual risk, clinicians may consider liver blood tests, noninvasive fibrosis assessment, imaging and management of weight and other cardiometabolic risk factors.

Emotional Health and Diabetes Distress

Living with diabetes can be emotionally demanding. Diabetes distress, depression, anxiety and fear of hypoglycemia can interfere with glucose monitoring, medication use, eating, exercise, sleep and medical follow-up.

The ADA Standards of Care in Diabetes—2026 emphasize routine assessment of behavioral and emotional health, including diabetes distress, depression, anxiety and fear of hypoglycemia.

Speak with your healthcare team if emotional stress is affecting your self-care, relationships, sleep, work or quality of life. Behavioral health support is a legitimate part of diabetes care.

Can Diabetes Complications Be Prevented?

Not every complication can be completely prevented, but many risks can be reduced and many problems can be detected earlier.

Important prevention strategies include:

• work toward your individualized glucose and A1C goals;
• avoid repeated severe hypoglycemia;
• manage blood pressure;
• manage LDL cholesterol and other cardiovascular risks;
• avoid smoking and tobacco;
• stay physically active when medically appropriate;
• take prescribed medicines consistently;
• protect kidney health;
• attend recommended eye examinations;
• check the feet regularly;
• treat infections and wounds early;
• maintain regular dental care;
• keep vaccinations up to date when recommended; and
• address sleep, depression, anxiety and diabetes distress.

Diabetes Complication Screening Checklist

Current ADA guidance recommends kidney assessment at least annually in all people with type 2 diabetes and in people with type 1 diabetes of sufficient duration. People who already have chronic kidney disease may require more frequent monitoring.

A comprehensive foot evaluation is also recommended at least annually, with more frequent examination for people who have loss of sensation, previous ulceration, amputation or other high-risk findings.

Who Has a Higher Risk of Diabetes Complications?

Risk may be higher when one or more of the following are present:

• glucose levels that remain above the individualized target;
• long duration of diabetes;
• high blood pressure;
• high LDL cholesterol or other lipid abnormalities;
• smoking or tobacco use;
• chronic kidney disease;
• cardiovascular disease;
• obesity or excess abdominal weight;
• frequent or severe hypoglycemia;
• neuropathy;
• poor circulation;
• previous foot ulcer or amputation;
• recurrent infections;
• missed insulin or other essential medication; or
• difficulty obtaining consistent medical care.

Having risk factors does not mean that complications are certain. It means that prevention, screening and early treatment become even more important.

Frequently Asked Questions About Diabetes Complications

Key Medical Takeaways

Related Diabetes Complication Guides

Medical References