Which are the three major complications of diabetes mellitus?

• A. Large vessel disease; Small vessel disease; Increased susceptibility to infections
• B. Neuropathy; Nephropathy; Retinopathy
• C. Hypertension; Hyperlipidemia; Obesity
• D. Gingivitis; Periodontitis; Halitosis

Answer: (A)

The main idea here is that diabetes mellitus causes complications in two broad vascular systems plus a heightened infection risk. The three major categories are damage to large vessels (macrovascular disease), damage to small vessels (microvascular disease), and an increased susceptibility to infections due to immune dysfunction and impaired healing. The option that lists large vessel disease, small vessel disease, and increased susceptibility to infections matches these three overarching areas, making it the best choice.

Neuropathy, nephropathy, and retinopathy are indeed important microvascular complications, but they are specific examples within the microvascular category rather than the three broad categories themselves. The remaining options mix risk factors or non-systemic issues (like gingivitis or obesity) that aren’t the three major systemic complications of diabetes.