**Core Concept**
Diabetes mellitus type-II is a chronic metabolic disorder characterized by insulin resistance and impaired insulin secretion, leading to hyperglycemia. This condition increases the risk of various complications, including cardiovascular, renal, and neurological disorders.

**Why the Correct Answer is Right**
The complications of diabetes mellitus type-II typically occur around 10-20 years after the onset of the disease. This is because the body's ability to compensate for the insulin resistance is gradually lost, leading to progressive beta-cell dysfunction and hyperglycemia. The increased glucose levels and insulin resistance contribute to the development of microvascular and macrovascular complications. The key pathological mechanisms involve advanced glycosylation end-products (AGEs), oxidative stress, and inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:**
Diabetes mellitus type-II is not typically considered a complication of another disease, but rather a chronic condition itself.

**Option B:**
While the exact timeline may vary, complications of diabetes mellitus type-II do not usually occur immediately after the onset of the disease.

**Option C:**
The exact time frame for the occurrence of complications in diabetes mellitus type-II is not 5 years, but rather 10-20 years after the onset of the disease.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the risk of complications in diabetes mellitus type-II can be significantly reduced through timely diagnosis, aggressive glycemic control, and regular monitoring. Early intervention can prevent or delay the onset of microvascular and macrovascular complications.

**Correct Answer:** C. 10-20 years