Why screen for Diabetic Nephropathy (DN) upon diagnosis of Type 2 Diabetes Mellitus (Type 2 DM), but only after 5 years for Type 1 Diabetes Mellitus (Type 1 DM)?

From the Guidelines

Screening for diabetic nephropathy should begin immediately upon diagnosis of Type 2 diabetes, but can be delayed until 5 years after diagnosis for Type 1 diabetes, as recommended by the 2023 guidelines for laboratory analysis in the diagnosis and management of diabetes mellitus 1. This approach is based on the differences in disease progression and pathophysiology between Type 1 and Type 2 diabetes. Key factors to consider include:

• The insidious development of Type 2 diabetes, which may remain undetected for years, resulting in potential kidney damage at the time of diagnosis
• The unknown exact onset of Type 2 diabetes, with patients possibly having asymptomatic hyperglycemia for 4-7 years before clinical diagnosis
• The more acute onset of Type 1 diabetes, with obvious symptoms leading to prompt diagnosis and rare development of nephropathy within the first 5 years
• The importance of early detection through annual urine albumin-to-creatinine ratio testing and serum creatinine measurement to calculate estimated glomerular filtration rate, as outlined in the guidelines 1
• The potential for interventions like optimizing glycemic control, blood pressure management, and initiating medications such as ACE inhibitors or ARBs to slow progression of kidney disease, which can significantly impact morbidity, mortality, and quality of life. Some key points to consider when screening for diabetic nephropathy include:
• Using morning spot urine albumin-to-creatinine ratio (uACR) for measurement, with a first morning void urine sample preferred 1
• Repeating uACR every 6 months 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
• Utilizing semiquantitative uACR dipsticks to detect early kidney disease and assess cardiovascular risk when quantitative tests are not available, with a positive result in >85% of individuals with moderately increased albuminuria 1

From the Research

Screening for Diabetic Nephropathy

• The American Diabetes Association recommends screening for chronic kidney disease (CKD) in patients with Type 2 diabetes at the time of diagnosis, and at least annually thereafter 2.
• This is because diabetic nephropathy is a common complication of Type 2 diabetes, and early detection and treatment can slow its progression 3.
• In contrast, patients with Type 1 diabetes are typically screened for diabetic nephropathy 5 years after diagnosis, as the risk of developing nephropathy is lower in the first 5 years after diagnosis 4.

Rationale for Different Screening Recommendations

• The difference in screening recommendations between Type 1 and Type 2 diabetes may be due to the fact that Type 2 diabetes is often diagnosed later in the course of the disease, when complications such as nephropathy may already be present 2.
• Additionally, patients with Type 2 diabetes are more likely to have other risk factors for nephropathy, such as hypertension and obesity, which may increase their risk of developing kidney disease 5.
• In contrast, patients with Type 1 diabetes are typically diagnosed at a younger age, and may not have the same level of risk factors for nephropathy, which may explain why screening is typically delayed until 5 years after diagnosis 4.

Importance of Early Screening and Detection

• Early screening and detection of diabetic nephropathy are critical, as they allow for early intervention and treatment, which can slow the progression of the disease 6, 3.
• Several biomarkers, including microalbuminuria, have been identified as early markers of diabetic nephropathy, and may be used to screen for the disease 3.
• Novel agents and therapies are also being developed to prevent or slow the progression of diabetic nephropathy, and early detection and treatment may improve outcomes for patients with the disease 2, 5.