**Core Concept**
Chronic adrenal insufficiency, also known as Addison's disease, is a condition where the adrenal glands do not produce sufficient cortisol and aldosterone hormones. This leads to a deficiency in the body's ability to regulate electrolyte balance, blood pressure, and response to stress.

**Why the Correct Answer is Right**
Chronic adrenal insufficiency typically presents with symptoms such as weight loss, fatigue, hypotension, hyperpigmentation, and electrolyte imbalances. The deficiency of cortisol and aldosterone hormones can lead to an inability to regulate sodium and potassium levels, causing hypokalemia and hyponatremia. Additionally, the lack of cortisol can impair the body's response to stress, leading to an increased susceptibility to infections and hypoglycemia.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because chronic adrenal insufficiency is characterized by an inability to produce cortisol and aldosterone, not an overproduction.
**Option B:** This option is incorrect because hyperkalemia is a consequence of primary aldosteronism (Conn's syndrome), not chronic adrenal insufficiency.
**Option C:** This option is incorrect because hyperglycemia is typically seen in Cushing's syndrome, a condition characterized by excess cortisol production, not chronic adrenal insufficiency.

**Clinical Pearl / High-Yield Fact**
Chronic adrenal insufficiency can be caused by autoimmune destruction of the adrenal glands, tuberculosis, or other infections, and can be diagnosed with a 9 AM cortisol level and a short Synacthen test.

**Correct Answer: C. Hyperglycemia**