## Core Concept
Acarbose is an anti-diabetic drug used in the management of type 2 diabetes mellitus. It belongs to the class of alpha-glucosidase inhibitors, which work by delaying carbohydrate absorption in the gut. This mechanism helps in reducing postprandial blood glucose levels.

## Why the Correct Answer is Right
The correct statement about acarbose is that it works by inhibiting intestinal alpha-glucosidases, which delays carbohydrate absorption. This results in a decrease in postprandial glucose levels. Acarbose is known to cause gastrointestinal side effects like flatulence, diarrhea, and abdominal pain due to its mechanism of action.

## Why Each Wrong Option is Incorrect
- **Option A:** If option A states that acarbose works by stimulating insulin secretion, it is incorrect because acarbose does not directly stimulate insulin secretion; it acts locally in the gut to delay carbohydrate absorption.
- **Option B:** If option B mentions that acarbose can cause lactic acidosis, it might be misleading as lactic acidosis is more commonly associated with biguanides like metformin, not typically with acarbose.
- **Option C:** If option C suggests that acarbose is effective in reducing HbA1c levels, it is true and not the false statement we're looking for.
- **Option D:** If option D states that acarbose can be used in patients with renal impairment without dose adjustment, it might be incorrect because while acarbose itself is not significantly affected by renal impairment, its use in significant renal impairment could be cautious due to potential complications, but it's not the most directly false statement compared to mechanisms or common side effects.

## Clinical Pearl / High-Yield Fact
Acarbose is known for its gastrointestinal side effects, which can limit its tolerability. A key clinical pearl is that these side effects can be minimized by starting with a low dose and gradually increasing it. Additionally, acarbose should be taken at the start of a meal to effectively delay carbohydrate absorption.

## Correct Answer: D.