NDT Advance Access originally published online on July 22, 2006
Nephrology Dialysis Transplantation 2006 21(12):3608-3609; doi:10.1093/ndt/gfl435
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Associations of chronic kidney disease with the metabolic syndrome in non-diabetic elderly
Email: kanauchi{at}nmu-gw.naramed-u.ac.jpSir,
Chronic kidney disease (CKD) and the metabolic syndrome are worldwide public health problems. Few studies have reported that persons with mildly reduced kidney function are at greater risk for cardiovascular disease [1], but it remains unclear whether CKD contributes to prevalent metabolic syndrome in non-diabetic population. In addition, there are no studies that have focused on the elderly to evaluate the relationship between level of kidney function and prevalent metabolic syndrome.
The study sample was drawn from a database of 954 Japanese who had undergone a 75 g oral glucose tolerance test (OGTT) as part of an evaluation for glucose intolerance. Only older individuals, 
65 years of age, were included in the present analysis. Exclusion criteria were overt diabetes; fasting hyperglycaemia 7.0 mmol/l or 2 h plasma glucose 11.1 mmol/l; or those with signs of serious diseases which affect insulin sensitivity. Hence, a total of 315 non-diabetic elderly were included in the present analysis. Estimated glomerular filtration rate (eGFR) was calculated by using the equation developed by the Modification of Diet in Renal Disease (MDRD) study [2]. We calibrated eGFR values for smaller Japanese subjects (x0.881) recommended by the Japanese Society of Nephrology. The metabolic syndrome was defined according to the revised criteria of the National Cholesterol Education Program Adult Treatment Panel III (ATPIII), recently recommended from the American Heart Association/National Heart, Lung, and Blood Institute [3]. Insulin sensitivity was measured by the homoeostasis model assessment of insulin resistance (HOMA-R) [4].
Of the 315 subjects included in the analysis, the mean age was 71.5 ± 5.2 year, 36.8% were female and mean body mass index was 23.4 ± 3.1 kg/m2. The mean serum creatinine was 79.7 µmol/l with a range of 38.9–213.9 µmol/l, and the eGFR was 77.6 ml/min per 1.73 m2, with a range of 23.4 to 144.5 ml/min per 1.73 m2. Age tended to increase and total cholesterol tended to decrease in the groups with lower eGFR. By logistic regression analysis adjusted for potential confounding factors, reduced kidney function was independently associated with an increased risk for prevalent metabolic syndrome (Table 1).
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Prior study has been consistent in showing an association between decreased kidney function and increased insulin resistance even in patients with incipient kidney disease [1]. In the Third National Health and Nutrition Examination Survey, insulin resistance estimated by HOMA-R was associated with an increased risk for CKD in non-diabetic participants [5]. But, it remains unknown whether CKD is associated with the metabolic syndrome in non-diabetic elderly. Our study has several strengths, including the large number of subjects who had undergone 75 g OGTT, exclusion of individuals with diabetes and adjustment for a number of potential confounding factors, such as insulin resistance (HOMA-R). But, several limitations may affect the interpretation of our results. First, we selected a relatively high-risk population who had undergone 75 g OGTT. Second, we applied the revised ATPIII criteria in this study. When applying the revised criteria (as a glucose cutoff point of 5.6 mmol/l and a lower threshold of waist) instead of the original ATPIII criteria, the prevalence of the metabolic syndrome might be overestimated in our subjects compared with those in non-institutionalized population. Third, we used the MDRD equation to estimate GFR. The MDRD equation was validated in both White and Black population, but the precise calibration of this equation for Japanese has not been established. Because Japanese have smaller body mass for whites, we calibrated eGFR values using a recommendation by the Japanese Society of Nephrology. On the basis of our results, the mildly decreased kidney function as well as chronic kidney disease might be an important factor for the metabolic syndrome even after adjusting for insulin resistance in non-diabetic elderly Japanese.
Conflict of interest statement. None declared.
1First Department of
Internal Medicine
Nara Medical University
Kashihara, Nara
2Health Care Unit
SHARP Corporation, Japan
References
- Fliser D, Pacini G, Engelleiter R, et al. (1998) Insulin resistance and hyperinsulinemia are already present in patients with incipient renal disease. Kidney Int 53:1343–1347.[CrossRef][Web of Science][Medline]
- National Kidney Foundation Kidney Disease Outcome Quality Initiative (K/DOQI) Advisory Board. (2002) K/DOQI clinical practice guidelines for chronic kidney disease. Am J Kidney Dis 39:Suppl 2, S32–S33.[CrossRef]
- Grundy SM, Brewer Jr HB, Cleeman JI, et al. (2004) Definition of metabolic syndrome. Circulation 109:433–438.
[Free Full Text] - Matthews DR, Hosker JP, Rudenski AS, et al. (1985) Homeostasis model assessment. Diabetologia 28:412–419.[CrossRef][Web of Science][Medline]
- Chen J, Muntner P, Hamm LL, et al. (2003) Insulin resistance and risk of chronic kidney disease in nondiabetic US adults. J Am Soc Nephrol 14:469–477.
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