Which condition is characterized by extreme thirst and unexplained weight loss?

The condition characterized by extreme thirst and unexplained weight loss is diabetes. This metabolic disorder results from high levels of glucose in the blood, either due to the body's inability to produce insulin (Type 1 diabetes) or the body's cells becoming resistant to insulin (Type 2 diabetes).

Extreme thirst, or polydipsia, occurs because the body attempts to balance out the high glucose levels by prompting increased fluid intake. Unexplained weight loss happens as the body starts to break down muscle and fat for energy when it can't effectively use glucose due to insufficient insulin.

In contrast, hypoglycemia refers to low blood sugar levels, which typically leads to symptoms like shakiness, sweating, and confusion rather than extreme thirst or weight loss. Acanthosis nigricans is a skin condition often associated with insulin resistance, generally manifesting as dark patches rather than acute thirst or weight loss. Hyperglycemia refers to high blood sugar but is more of a symptom of diabetes rather than the full condition itself, which encompasses a broader range of symptoms including those mentioned.