The signs and symptoms of type 1 diabetes in children usually develop quickly, over a period of weeks. Look for:

• Increased thirst and frequent urination. As excess sugar builds up in your child’s bloodstream, fluid is pulled from the tissues. This may leave your child thirsty. As a result, your child may drink — and urinate — more than usual.
• Extreme hunger. Without enough insulin to move sugar into your child’s cells, your child’s muscles and organs become energy-depleted. This triggers intense hunger.
• Weight loss. Despite eating more than usual to relieve hunger, your child may lose weight — sometimes rapidly. Without the energy sugar supplies, muscle tissues and fat stores simply shrink. Unexplained weight loss is often the first sign to be noticed.
• Fatigue. If your child’s cells are deprived of sugar, he or she may become tired and lethargic.
• Irritability or unusual behavior. Children with undiagnosed type 1 diabetes may suddenly seem moody or irritable.
• Blurred vision. If your child’s blood sugar is too high, fluid may be pulled from the lenses of your child’s eyes. This may affect your child’s ability to focus clearly.
• Yeast infection. Girls with type 1 diabetes may have a genital yeast infection, and babies can develop diaper rash caused by yeast.