• High blood sugar (hyperglycemia). Your blood sugar level can rise for many reasons, including eating too much, being sick or not taking enough glucose-lowering medication.
• Increased ketones in your urine (diabetic ketoacidosis). If your cells are starved for energy, your body may begin to break down fat. This produces potentially toxic acids known as ketones.
• Low blood sugar (hypoglycemia). If your blood sugar level drops below your target range, it's known as low blood sugar. Your blood sugar level can drop for many reasons, including skipping a meal and getting more physical activity than normal. However, low blood sugar is most likely if you take glucose-lowering medications that promote the secretion of insulin or if you're receiving insulin therapy.
Long-term complications of diabetes develop gradually. The earlier you develop diabetes — and the less controlled your blood sugar — the higher the risk of complications. Eventually, diabetes complications may be disabling or even life-threatening.
• Cardiovascular disease. including coronary artery disease with chest pain (angina), heart attack, stroke and narrowing of arteries (atherosclerosis).
• Nerve damage (neuropathy). This can cause tingling, numbness, burning or pain that usually begins at the tips of the toes or fingers and over a period of months or years gradually spreads upward. Damage to the nerves related to digestion can cause problems with nausea, vomiting, diarrhea or constipation. For men, it may lead to problems with erectile dysfunction.
• Kidney damage (nephropathy). Severe damage can lead to kidney failure or irreversible end-stage kidney disease, requiring dialysis or a kidney transplant.
• Eye damage. Diabetes can damage the blood vessels of the retina (diabetic retinopathy), potentially leading to blindness.
• Foot damage. Nerve damage in the feet or poor blood flow to the feet increases the risk of various foot complications. Left untreated, cuts and blisters can become serious infections. Severe damage might require toe, foot or even leg amputation.
• Skin and mouth conditions. Diabetes may leave you more susceptible to skin problems, including bacterial infections, fungal infections and itching. Gum infections also may be a concern, especially if you have a history of poor dental hygiene.
• Bone and joint problems. Diabetes may put you at risk of bone and joint problems such as osteoporosis.
Complications of gestational diabetes
Most women who have gestational diabetes deliver healthy babies. However, untreated or uncontrolled blood sugar levels can cause problems for you and your baby.
Complications in your baby can occur as a result of gestational diabetes:
• Excess growth. Extra glucose can cross the placenta, which triggers your baby's pancreas to make extra insulin. This can cause your baby to grow too large (macrosomia). Very large babies are more likely to become wedged in the birth canal, sustain birth injuries or require a C-section birth.
• Low blood sugar. Sometimes babies of mothers with gestational diabetes develop low blood sugar (hypoglycemia) shortly after birth because their own insulin production is high. Prompt feedings and sometimes an intravenous glucose solution can return the baby's blood sugar level to normal.
• Respiratory distress syndrome. If your baby is delivered early, respiratory distress syndrome — a condition that makes breathing difficult — is possible. Babies who have respiratory distress syndrome may need help breathing until their lungs become stronger.
• Jaundice. This yellowish discoloration of the skin and the whites of the eyes may occur if a baby's liver isn't mature enough to break down a substance called bilirubin, which normally forms when the body recycles old or damaged red blood cells. Although jaundice usually isn't a cause for concern, careful monitoring is important.
• Type 2 diabetes later in life. Babies of mothers who have gestational diabetes have a higher risk of developing obesity and type 2 diabetes later in life.
• Death. Rarely, untreated gestational diabetes results in a baby's death either before or shortly after birth.
Complications in you can also occur as a result of gestational diabetes:
• Preeclampsia. This condition is characterized by high blood pressure and excess protein in the urine. Left untreated, preeclampsia can lead to serious or even life-threatening complications for both mother and baby.
• Subsequent gestational diabetes. Once you've had gestational diabetes in one pregnancy, you're more likely to have it again with the next pregnancy. You're also more likely to develop diabetes — typically type 2 diabetes — as you get older.
Complications of prediabetes
Prediabetes may develop into type 2 diabetes.