An A1C test provides an average measure of your blood sugar levels over the preceding two to three months. This test is a standard tool for monitoring diabetes and offers insights into how well blood sugar has been managed over time. Understanding your A1C level is a step in assessing your overall health, particularly concerning the long-term well-being of your kidneys.
Understanding A1C and Kidney Function
The A1C test measures glycated hemoglobin, which is hemoglobin in red blood cells that has sugar attached to it. Since red blood cells typically live for about three months, the A1C percentage reflects the average amount of sugar in your bloodstream during that period. A higher A1C percentage indicates higher average blood sugar levels.
Your kidneys perform several functions, including filtering waste products from your blood, balancing fluid and electrolyte levels, and producing hormones that help regulate blood pressure and red blood cell production. Sustained high blood sugar, indicated by an elevated A1C, can strain these delicate filtering units within the kidneys.
How Elevated A1C Damages Kidneys
Chronically elevated A1C levels can damage the kidneys’ tiny blood vessels, known as glomeruli. These glomeruli are responsible for filtering waste and excess fluids from the blood. Over time, high glucose levels can make these vessels narrow and stiff, impairing their function.
This damage can lead to a “leaky barrier” within the kidneys, allowing proteins, such as albumin, to spill into the urine. The kidneys may also become less effective at removing water, salt, and other waste products from the body. This continuous process of damage and impaired filtering ability is often referred to as diabetic kidney disease. High blood sugar can also damage nerves, including those that control the bladder, leading to issues like incomplete bladder emptying, which can further stress the kidneys due to increased pressure.
A1C Levels and Kidney Disease Risk
Normal A1C levels range from 4.0% to 5.9% for individuals without diabetes. An A1C level between 5.7% and 6.4% is considered prediabetes, indicating an increased risk for developing type 2 diabetes. Even within this prediabetes range, there is an increased risk of kidney dysfunction and an elevated albumin-to-creatinine ratio (ACR), which suggests early kidney damage.
For individuals with diabetes, an A1C of 6.5% or higher is used for diagnosis. The goal for most people with diabetes is an A1C reading below 7.0% to reduce the risk of complications, including kidney problems. Maintaining A1C levels close to normal can significantly decrease the risk of diabetes-related complications. While a target of less than 7.0% is recommended for kidney protection, individualized A1C goals are set by healthcare providers based on factors like age, other health conditions, and risk of low blood sugar.
Protecting Kidney Health
Managing A1C levels is a primary step in protecting kidney function for individuals with or at risk of kidney disease. Adhering to prescribed medications for diabetes and blood pressure is a component of this management. Certain medications, such as ACE inhibitors, ARBs, SGLT2 inhibitors, and GLP-1 receptor agonists, can help lower blood sugar and blood pressure, thereby protecting the kidneys.
Lifestyle modifications also play a role in managing A1C and supporting kidney health. Adopting a healthy diet that emphasizes high-fiber foods and lean proteins while limiting sugary drinks and highly processed foods can help manage blood sugar levels. Regular physical activity, aiming for at least 150 minutes of moderate-intensity aerobic exercise per week along with strength training, helps lower blood sugar and reduce stress on the kidneys. Consistent monitoring of A1C and kidney function tests, such as urine protein tests, allows for early detection of changes and timely adjustments to treatment plans.