If blood sugar levels are not controlled early on in the course of diabetes, it can lead to a variety of serious health complications. These complications can be both short-term and long-term.

Short-term complications of uncontrolled blood sugar include:

1. Hypoglycemia (low blood sugar): This can occur if blood sugar levels drop too low as a result of taking too much insulin or other diabetes medications.

2. Hyperglycemia (high blood sugar): This can occur if blood sugar levels are consistently high and can lead to symptoms such as increased thirst, frequent urination, and fatigue.

3. Diabetic ketoacidosis (DKA): This is a potentially life-threatening complication that can occur if blood sugar levels become very high and the body starts breaking down fat for energy, resulting in the production of acidic ketones in the blood.

Long-term complications of uncontrolled blood sugar include:

1. Cardiovascular disease: High blood sugar levels can damage blood vessels and increase the risk of heart attack, stroke, and other cardiovascular problems.

2. Kidney disease: Uncontrolled diabetes can damage the kidneys over time, leading to kidney failure.

3. Nerve damage: High blood sugar levels can damage the nerves, leading to numbness, tingling, and pain in the hands and feet.

4. Eye damage: Uncontrolled diabetes can damage the blood vessels in the eyes, leading to diabetic retinopathy, a condition that can cause blindness.

5. Foot problems: Nerve damage and poor circulation can lead to foot problems, including ulcers, infections, and even amputation.

6. Skin conditions: Uncontrolled diabetes can cause skin conditions such as fungal infections, bacterial infections, and itching.

7. Dental problems: High blood sugar levels can increase the risk of gum disease, tooth decay, and other dental problems.

8. Digestive issues: Uncontrolled diabetes can lead to digestive problems such as gastroparesis (delayed stomach emptying) and diarrhea.

9. Hearing loss: Uncontrolled diabetes can damage the nerves and blood vessels in the ears, leading to hearing loss.

10. Mental health issues: Uncontrolled diabetes can increase the risk of depression, anxiety, and other mental health problems.

Overall, it is important to work with a healthcare provider to manage blood sugar levels effectively and prevent these potential complications. Early intervention and treatment are critical for preventing long-term health problems.