Diabetes complications fall into two groups: acute problems such as hypoglycemia and diabetic ketoacidosis, and chronic problems that develop over years, including cardiovascular disease, kidney disease, eye damage (retinopathy), nerve damage (neuropathy), foot ulcers, skin and dental infections, and mental health conditions. According to the CDC, adults with diabetes are two to three times more likely to die from heart disease and are the leading group needing dialysis and non-traumatic amputations. Good blood sugar, blood pressure, and cholesterol control can delay or prevent most of them.
Acute Complications
Hypoglycemia (Low Blood Sugar)
Blood glucose below 70 mg/dL can cause shakiness, sweating, confusion, and in severe cases seizure or loss of consciousness. It is most common in people using insulin or sulfonylureas. Treat with 15 grams of fast-acting carbs, wait 15 minutes, and recheck.
Diabetic Ketoacidosis (DKA)
DKA is an emergency mostly seen in type 1 diabetes, though it can occur in type 2, especially with SGLT2 inhibitors or during severe illness. Hallmarks are very high blood sugar, high ketones, nausea, abdominal pain, rapid breathing, and fruity breath. Hospital treatment with IV fluids, insulin, and electrolyte replacement is required.
Hyperosmolar Hyperglycemic State (HHS)
HHS is the type 2 counterpart to DKA: extremely high blood sugar (often above 600 mg/dL) with severe dehydration but minimal ketones. It carries a high mortality rate and requires emergency care.
Chronic Complications Overview
| Complication | Typical Onset | Screening | Severity |
|---|---|---|---|
| Cardiovascular disease | 5-15 years | Lipid panel, BP yearly | Leading cause of death |
| Diabetic kidney disease | 5-20 years | Urine albumin + eGFR yearly | Can progress to dialysis |
| Retinopathy | 5-15 years | Dilated eye exam yearly | Leading cause of adult blindness |
| Peripheral neuropathy | 5-10 years | Annual foot exam | Pain, numbness, ulcer risk |
| Autonomic neuropathy | 10-20 years | Symptom-based | Affects digestion, heart rate, bladder |
| Foot ulcers / amputation | Any time if neuropathy | Daily self-check + yearly podiatry | Amputation in severe cases |
| Skin conditions | Any time | Self-check | Usually manageable |
| Periodontal (gum) disease | Any time | Dental exam every 6 months | Common; worsens control |
| Depression / diabetes distress | Any time | PHQ-9 yearly | Affects self-care |
| Sexual dysfunction | 5-15 years | Symptom-based | Common but often treatable |
Cardiovascular Disease
According to the CDC, adults with diabetes are two to three times more likely to have a heart attack or stroke than those without. Diabetes damages blood vessels and accelerates atherosclerosis. Risk factors multiply: high LDL cholesterol, high blood pressure, smoking, and obesity.
Preventive steps include:
- LDL cholesterol usually below 100 mg/dL, or below 70 if you already have heart disease
- Blood pressure below 130/80
- Aspirin for some adults with established cardiovascular disease
- Weight management, not smoking, and regular exercise
- GLP-1 agonists or SGLT2 inhibitors for added cardiovascular protection in many adults with type 2 diabetes
Diabetic Kidney Disease (Nephropathy)
Diabetes is the leading cause of kidney failure in the United States. Damage starts silently; small amounts of albumin in the urine are the earliest sign. Over years, kidney filters (glomeruli) lose function until dialysis or transplant is needed.
Screen yearly with a urine albumin-to-creatinine ratio and eGFR blood test. ACE inhibitors, ARBs, and SGLT2 inhibitors protect the kidneys. Learn more in our diabetic kidney disease guide.
Diabetic Retinopathy and Other Eye Problems
High blood sugar damages tiny retinal blood vessels. Non-proliferative retinopathy causes microaneurysms and hemorrhages; proliferative retinopathy leads to new, fragile vessels that can bleed or detach the retina. Diabetes also increases cataracts and glaucoma risk.
The ADA recommends a dilated eye exam at diagnosis of type 2 diabetes and within five years for type 1, then yearly. Treatments include laser photocoagulation, anti-VEGF injections, and surgery for advanced cases.
Peripheral Neuropathy
About half of adults with diabetes eventually develop nerve damage. Peripheral neuropathy causes numbness, tingling, burning, or pain, typically starting in the toes and moving up. It is the main reason foot ulcers occur: when you cannot feel a blister, it can progress to infection and amputation.
Tight glucose control is the best prevention. Medications such as duloxetine, pregabalin, and gabapentin treat painful neuropathy. See our articles on neuropathy symptoms for more detail.
Autonomic Neuropathy
Autonomic neuropathy affects the involuntary nervous system and can cause:
- Gastroparesis (slow stomach emptying, nausea, erratic blood sugars)
- Orthostatic hypotension (dizziness on standing)
- Resting tachycardia (high resting heart rate)
- Bladder dysfunction
- Erectile dysfunction
- Sweating abnormalities
- Hypoglycemia unawareness
Foot Complications
Diabetes is the top cause of non-traumatic lower-limb amputation. The pathway is usually neuropathy + poor circulation + a wound. Prevention is highly effective:
- Inspect feet daily for cuts, blisters, redness, or swelling
- Wash and dry thoroughly; moisturize but not between toes
- Trim nails straight across; avoid bathroom surgery
- Wear well-fitting shoes and seamless socks
- Never go barefoot
- Get an annual comprehensive foot exam and more often if you have neuropathy
Skin Conditions
Diabetes raises risk for bacterial infections (boils, cellulitis), fungal infections (yeast, athlete’s foot), acanthosis nigricans (dark velvety patches in skin folds, an insulin-resistance sign), diabetic dermopathy (shin spots), and slow wound healing.
Dental Disease
Gum disease is both more common and more severe in people with diabetes, and untreated gum disease worsens blood sugar control. Brush and floss daily and get cleanings every six months.
Mental Health
Adults with diabetes are two to three times more likely to experience depression, and many also experience “diabetes distress,” the burnout from constant self-management demands. Screening and treatment (therapy, medication, diabetes education) improve both mental health and A1C.
Sexual Health
Both men and women with diabetes experience higher rates of sexual dysfunction. Men may develop erectile dysfunction due to nerve and vascular damage. Women may experience vaginal dryness, decreased arousal, and more yeast infections. Many effective treatments exist; bring it up with your doctor.
How to Cut Your Risk Dramatically
Landmark trials including the UKPDS, DCCT, and ACCORD studies established that tight control of A1C, blood pressure, and LDL cholesterol reduces complication rates by 30-60 percent over 10-15 years. Key targets for most adults:
| Metric | Target |
|---|---|
| A1C | Less than 7% |
| Blood pressure | Less than 130/80 |
| LDL cholesterol | Less than 100 (70 if prior CVD) |
| Tobacco | None |
| Physical activity | 150+ min/week moderate intensity |
Why Prediabetes Matters
Damage does not wait for a diabetes diagnosis. Retinopathy, kidney changes, and cardiovascular disease all begin during prediabetes. That is why reversing prediabetes through lifestyle change is so valuable. See our reverse prediabetes and prediabetes overview for a detailed playbook, and our high blood pressure guide for cardiovascular risk management.
When to Call Your Doctor
- Any non-healing foot wound
- Sudden or worsening vision change
- Swelling in legs or ankles, foamy urine, or unexplained fatigue
- Chest pain, shortness of breath, or symptoms of stroke
- Persistent blood sugars above 300 mg/dL
- Ketones in moderate or large amounts
- Signs of depression or overwhelming diabetes distress
The Bottom Line
Diabetes can affect nearly every organ system, from the heart and kidneys to the eyes, nerves, feet, skin, gums, and mind. Most long-term complications take 5-20 years to develop and can be delayed or prevented with steady control of A1C, blood pressure, and cholesterol, plus yearly screenings for eyes, kidneys, and feet. The work is real, but the payoff is enormous: decades of extra life and far fewer serious problems.
