**Core Concept**
The destruction of beta cells in the pancreas leads to a reduction in insulin production, causing hyperglycemia. The percentage of beta cell mass that needs to be destroyed to result in hyperglycemia is a critical threshold.

**Why the Correct Answer is Right**
The correct answer is based on the concept of beta cell mass and its relationship to insulin production. Beta cells are responsible for producing insulin, which regulates blood glucose levels. When a significant portion of beta cells is destroyed, the remaining cells cannot compensate for the loss, leading to hyperglycemia. The exact percentage of beta cell mass that needs to be destroyed to result in hyperglycemia is around 90% or more. This is because even a small amount of functioning beta cells can still produce enough insulin to maintain normal blood glucose levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the destruction of less than 90% of beta cell mass would still allow the remaining cells to produce enough insulin to maintain normal blood glucose levels.

**Option B:** This option is incorrect because the destruction of a smaller percentage of beta cell mass, such as 50-70%, would still allow the remaining cells to produce enough insulin to maintain normal blood glucose levels.

**Option C:** This option is incorrect because the destruction of a larger percentage of beta cell mass, such as 99%, would result in a complete loss of insulin production, leading to severe hyperglycemia and potentially life-threatening complications.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the destruction of 90% or more of beta cell mass is a critical threshold for the development of hyperglycemia. This knowledge is crucial for diagnosing and managing diabetes mellitus.

**Correct Answer: D.**