I read with interest the Case Study by Souraty et al. entitled 'Nodular glomerulosclerosis in a patient with metabolic syndrome without diabetes' in the November 2008 issue of Nature Clinical Practice Nephrology.1 This case has many flaws and it is not a sound basis on which to draw such strong conclusions as those stated by the authors. I believe that the patient in question had idiopathic glomerulosclerosis, and that the findings were overstretched to attribute the renal disease to metabolic syndrome.
The authors do not mention that the patient is obese (other than that he has central obesity), despite the fact that his BMI is 33.7 kg/m2 (height 173 cm; weight 101 kg). The authors do state the patient's waist circumference (114 cm), but obese patients, especially those with a BMI greater than 31 kg/m2, are at high risk of cardiovascular disease, irrespective of whether their waist circumference is less than or greater than 104 cm. The authors state that the patient has hypertension but do not mention whether he is on any medications for this condition.
The authors ruled out the diagnosis of diabetes mellitus and state that most of the patient's blood glucose readings (fasting and random) were around 5.3 mmol/l (range 3.6–6.5 mmol/l). During oral glucose tolerance testing, the patient's fasting glucose was 5.6 mmol/l and his 2 h glucose level was 4.4 mmol/l. These results do not meet any definition of dysglycemia, whether defined by impaired fasting glucose, impaired glucose tolerance or diabetes.2,3 However, the authors state that “The patient presented here met the criteria for metabolic syndrome by at least one of the two commonly used definitions since he had central obesity, increased blood pressure and impaired glucose tolerance.” Various definitions of metabolic syndrome exist4,5,6 and the patient barely fulfills the definition recommended by the International Diabetes Federation.6 The fact that the patient's triglyceride level was normal and that his HDL cholesterol level was reasonable for a man of this age creates further doubt about the diagnosis of metabolic syndrome.
I believe that this case does not fulfill the definition of metabolic syndrome and that the conclusion that “Patients with metabolic syndrome should be screened for evidence of renal injury” is not supported by the evidence presented. This is merely a case of idiopathic nodular glomerulosclerosis with a complicated past history. Early intervention and lifestyle changes can mitigate complications in a variety of pathologic processes and should be considered in this case because of the patient's obesity and cardiovascular risk factors, and not because of the supposed presence of metabolic syndrome.
Souraty, P et al . (2008) Nodular glomerulosclerosis in a patient with metabolic syndrome without diabetes. Nat Clin Pract Nephrol 4: 639–642
American Diabetes Association (2008) Diagnosis and classification of diabetes mellitus. Diabetes Care 31 (Suppl 1): S55–S60
Canadian Diabetes Association (2008) Definition, classification and diagnosis of diabetes and other dysglycemic categories. Can J Diabetes 32 (Suppl 1): S10–S12
Alberti, KG and Zimmet, PZ (1998) Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: diagnosis and classification of diabetes mellitus provisional report of a WHO consultation. Diabet Med 15: 539–553
Grundy, SM et al . (2005) Diagnosis and management of the metabolic syndrome: an American Heart Association/National Heart, Lung, and Blood Institute Scientific Statement. Circulation 112: 2735–2752
International Diabetes Federation (online 2006) The IDF consensus worldwide definition of the metabolic syndrome [http://www.idf.org/webdata/ docs/IDF_Meta_def_final.pdf] (accessed 1 November 2008)
The author declares no competing financial interests.
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Parmar, M. Overstated conclusions and overstretched diagnosis?. Nat Rev Nephrol 5, E1 (2009). https://doi.org/10.1038/ncpneph1034