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Case 169
Diagnosis
 
     
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Diagnosis: Early Diabetic Nephropathy (diffuse thickening of glomerular basement membranes only: Class I)

Although diabetic nephropathy (DN) is generally considered to develop after many years of disease progression (usually more than 10 years), metabolic control of the disease leads to much variability in the time of development of renal structural lesions. In cases of very poor control, lesions can be seen in the first years of the disease, it is even possible to find Kimmelstiel-Wilson nodules as fast as before 5 years if there has been very poor metabolic control. Early lesions, such as diffuse thickening of the glomerular basement membrane (GBM), can be seen before 3 years of evolution. That was the case with our patient.

GBM thickening is a characteristic early change in type 1 and type 2 DN and increases with duration of disease. GBM thickening is a consequence of extracellular matrix accumulation, with increased deposition of normal extracellular matrix components such as collagen types IV and VI, laminin, and fibronectin. Such accumulations result from increased production of these proteins, their decreased degradation, or a combination of the two. GBM thickening may already be present in type 1 diabetes patients who are normoalbuminuric. GBM thickening has even been described as a “prediabetic” lesion: In patients with proteinuria and isolatedGBM thickening but without overt diabetes (Tervaert TW, et al. Pathologic classification of diabetic nephropathy. J Am Soc Nephrol. 2010;21(4):556–563. [PubMed link]).

The American Diabetes Association and International Society of Nephrology recommend annual screening for albuminuria and also measurement of estimated glomerular filtration rate (eGFR) to identify and monitor diabetic nephropathy. Microalbuminuria is defined as albumin excretion rate (AER) ≥20ug/min or albumin creatinine ratio (ACR) ≥30mg/g, and have both been shown to be associated with expansion of the glomerular basement membrane in diabetic nephropathy (Bjornstad P, et al. Early diabetic nephropathy in type 1 diabetes: new insights. Curr Opin Endocrinol Diabetes Obes. 2014;21(4):279–286. [PubMed link]).

Early DN is a potentially reversible condition (He Y, et al. Reversal of Early Diabetic Nephropathy by Islet Transplantation under the Kidney Capsule in a Rat Model. J Diabetes Res. 2016;2016:4157313. [PubMed link]).

See the chapter The kidney in diabetes mellitus and other metabolic disorders of our tutorial.

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References

  • Gu D, Chen Y, Masucci M, Xiong C, Zou H, Holthofer H. Potential urine biomarkers for the diagnosis of prediabetes and early diabetic nephropathy based on ISN CKHDP program. Clin Nephrol. 2020;10.5414/CNP92S123. [PubMed link]
  • He Y, Xu Z, Zhou M, et al. Reversal of Early Diabetic Nephropathy by Islet Transplantation under the Kidney Capsule in a Rat Model. J Diabetes Res. 2016;2016:4157313. [PubMed link]
  • Bjornstad P, Cherney D, Maahs DM. Early diabetic nephropathy in type 1 diabetes: new insights. Curr Opin Endocrinol Diabetes Obes. 2014;21(4):279–286. [PubMed link].
  • Tervaert TW, Mooyaart AL, Amann K, et al. Pathologic classification of diabetic nephropathy. J Am Soc Nephrol. 2010;21(4):556–563. [PubMed link]

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