What is the significance of monitoring the Microalbumin (Microalbumin) to Creatinine ratio in patients with Diabetes Mellitus (DM)?

From the Guidelines

Microalbumin to creatinine ratio (UACR) should be monitored annually in patients with diabetes to screen for diabetic kidney disease, as recommended by the most recent guidelines 1. The test measures small amounts of albumin in the urine, which is an early indicator of kidney damage before clinical proteinuria develops.

Key Recommendations

• For patients with type 1 diabetes, UACR screening should begin 5 years after diagnosis, while those with type 2 diabetes should be screened at the time of diagnosis and yearly thereafter 1.
• A normal UACR is less than 30 mg/g, with 30-300 mg/g indicating microalbuminuria and values above 300 mg/g representing macroalbuminuria.
• If elevated levels are detected, the test should be repeated every 6 months to assess change among people with diabetes and hypertension, especially if estimated glomerular filtration rate is <60 mL/min/1.73 m2 and/or albuminuria is >30 mg/g creatinine in a spot urine sample 1.

Monitoring and Treatment

• The first morning void urine sample should be used for measurement of albumin-to-creatinine ratio, and if this is difficult to obtain, all urine collections should be at the same time of day, with the individual well hydrated and not having ingested food within the preceding 2 h or exercised 1.
• Once microalbuminuria is confirmed, treatment typically includes optimizing blood glucose control, blood pressure management with ACE inhibitors or ARBs as first-line agents, and lifestyle modifications including dietary protein moderation, smoking cessation, and regular physical activity 1.
• These interventions can slow progression of kidney disease and reduce cardiovascular risk in diabetic patients, and should be guided by regular monitoring of UACR and estimated glomerular filtration rate, at least annually, and 1-4 times per year depending on the stage of the disease 1.

From the FDA Drug Label

The RENAAL study was a randomized, placebo-controlled, double-blind, multicenter study conducted worldwide in 1513 patients with type 2 diabetes with nephropathy (defined as serum creatinine 1.3 to 3.0 mg/dL in females or males ≤60 kg and 1.5 to 3. 0 mg/dL in males >60 kg and proteinuria [urinary albumin to creatinine ratio ≥300 mg/g])

• Microalbumin to creatinine ratio is used to define nephropathy in the RENAAL study, with a ratio of ≥300 mg/g indicating proteinuria.
• The study monitored the urinary albumin to creatinine ratio at baseline, with a mean ratio of 1808 mg/g.
• Monitoring of microalbumin to creatinine ratio is important in patients with diabetes, as it can indicate the presence of nephropathy and help guide treatment decisions.
• The use of losartan in patients with type 2 diabetes and nephropathy has been shown to reduce the risk of doubling of serum creatinine and end-stage renal disease, and to decrease the level of proteinuria 2.

From the Research

Microalbumin to Creatinine Ratio Monitoring in Diabetes

• The microalbumin to creatinine ratio is a useful tool for screening and monitoring diabetic nephropathy in patients with diabetes 3, 4.
• Studies have shown that the albumin to creatinine ratio in an early morning urine sample is a reliable method for screening for microalbuminuria, with a sensitivity of 88-100% and specificity of 81-100% 3.
• A moderate positive correlation has been observed between microalbuminuria and urine albumin creatinine ratio, as well as between urine albumin creatinine ratio and plasma creatinine 4.
• Regular monitoring of microalbuminuria, urine albumin creatinine ratio, and HbA1c levels is recommended for type 2 diabetic patients who are at risk of developing renal impairment 4.

Treatment and Management

• Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) are commonly used to treat diabetic nephropathy, and combination therapy with both ACEIs and ARBs has been shown to be more effective than using either alone 5, 6.
• Recent trials have also elucidated the roles of additional therapeutic agents, including sodium-glucose cotransporter 2 inhibitors, glucagon-like peptide 1 receptor agonists, and mineralocorticoid receptor antagonists, in the treatment of chronic kidney disease in people with type 2 diabetes 7.
• Combination therapy with ACEIs and ARBs has been shown to reduce 24-hour proteinuria and slow the progression of diabetic nephropathy, although it may also be associated with small effects on glomerular filtration rate, serum creatinine, and potassium 5, 6.