SN instructed patient and caregiver on how the kidneys play an important role in the body: they filter the blood, removing waste products and excess salt and water. If the kidneys become diseased, they falter in their task, leaving the blood polluted.People with diabetes often focus on keeping their blood sugar levels in the right ranges. And while it is important to control blood sugar, it turns out that controlling blood pressure is at least as important. That's because high blood sugar and high blood pressure work in concert to damage the blood vessels and organ systems.