Interpretation Of Chinese Guidelines For Diabetic Nephropathy

Professor Sun Lin from the Nephrology Institute of Central South University/Department of Nephrology, Second Xiangya Hospital, shared with us the interpretation of the "Chinese Guidelines for Clinical Diagnosis and Treatment of Diabetic Kidney Diseases" formulated by the Nephrology Professional Committee of the Chinese Medical Association.

Click to cistanche herba for kidney disease

Professor Sun Lin pointed out that diabetic nephropathy is a common disease in China. The latest research shows that diabetic kidney disease (DKD) has replaced primary glomerular disease as the leading cause of chronic kidney disease (CKD) in China. DKD is also a leading cause of end-stage renal disease (ESRD) in developed countries. Therefore, the standardized diagnosis and treatment of DKD has become a topic of great concern in the field of kidney disease at home and abroad.

Diabetic retinopathy is not a requirement for the diagnosis of DKD

Guideline recommendation: Diabetic nephropathy retinopathy is an important basis for the diagnosis of DKD, but diabetic retinopathy is not a necessary condition for the diagnosis of diabetic kidney disease.

The results of a recent meta-analysis showed that the sensitivity of diabetic retinopathy to predict diabetic nephropathy was 0.65, the positive predictive value was 0.72, and the negative predictive value was 0.69. For proliferative diabetic retinopathy, the sensitivity was 0.25 and the specificity was 0.98.

In addition, the research of Chinese academician Chen Xiangmei's team and other scholars also found that the occurrence and development of diabetic nephropathy and retinopathy are not completely parallel. It is suggested that diabetic retinopathy can be used as an important basis for diabetic nephropathy, but it is not a necessary condition for diagnosis, because some patients with diabetic nephropathy may not be accompanied by retinopathy in the early stage.

Creatinine level does not determine whether to require dialysis

The guidelines suggest that patients with diabetic nephropathy should undergo hemodialysis or peritoneal dialysis when they have severe renal impairment, such as uncontrolled or corrected hypertension, refractory edema, heart failure, severe anemia, gastrointestinal poisoning symptoms, protein energy consumption, and severe metabolic disorders.

However, in the absence of the above conditions and signs, dialysis cannot be initiated according to the level of renal function. Many doctors believe that if the creatinine is significantly elevated, dialysis should be initiated when the creatinine level reaches 800, but if there are no symptoms and signs of uremia, dialysis should not be started just because the creatinine is significantly elevated. On the contrary, if the patient has the above symptoms, even if the creatinine is only more than 300, it is recommended to start dialysis treatment.

Studies have found that although dialysis can relieve the symptoms of patients with renal failure, early dialysis may increase the risk of death, and early dialysis should be avoided as much as possible. A foreign study also suggested that 60% of patients regret early dialysis.

The guidelines also suggest that early dialysis is not recommended for elderly patients with diabetic nephropathy and renal failure. The rationale is that elderly patients with diabetic nephropathy and renal failure are at increased risk for dialysis, and lung infections are particularly common.

In general, creatinine level cannot be used to determine whether a patient is translucent or opaque, so special attention should be paid to this point.

What is the trend of renal function changes in DKD patients with normal proteinuria?

Studies have shown that renal function in patients with normoproteinuric diabetes has a progressive decline after CKD stage 3, which is why eGFR<60 ml/(min·1.73 m²) is used as the cut-off value for normoproteinuric diabetes.

The light blue line in the figure below represents the ten-year follow-up of normal proteinuric diabetic patients with CKD stage 3. The results suggest that the average annual decline in eGFR in normal proteinuric type 1 and type 2 diabetic patients is 1.9 ml/min/1.73 m² after 10 years of follow-up.

The dark blue line and the red line represent the 10-year follow-up of CKD stage 3 patients with microalbuminuria and macroalbuminuria, respectively.

Director Sun Lin pointed out that for diabetic patients with normoproteinuria, lipid-lowering, RAS blockers, and other antihypertensive treatments are less intervened, and insufficient cardiorenal protection may be the reason for the continued deterioration of renal function, suggesting that we should increase our understanding and attention to normoproteinuric DKD.

Figure 1: Changes in proteinuria during 10-year follow-up in normoalbuminuric diabetic patients with CKD stage 3

A large RCT study showed that diabetic patients had a high incidence of normoproteinuria after CKD stage 3.

The study selected 15,773 patients with type 2 diabetes. Among the 1,673 patients with eGFR less than 60 ml/min/1.73 m², 56.6% were normal proteinuria, 30.8% were microalbuminuria, and 12.6% were macroalbuminuria.

Differences in urine metabolomics in normoproteinuric DKD patients suggest a different pathophysiological process than in non-DKD patients.

The study showed that there were 65 different metabolites among the simple diabetes group, normoalbuminuric DKD group, and proteinuric DKD group; the levels of linoleic acid, γ-linolenic acid, L-malic acid, and L-proline were different between the normoalbuminuric DKD group and the proteinuric DKD group.