Salt and excess food intake produced diabetic nephropathy in Japan

The purpose of this study is to retrospectively analyze the clinical characteristics of patients with diabetes mellitus who started dialysis therapy. First, we reviewed 120 cases of end-stage renal failure due to diabetic nephropathy who started dialysis therapy in 1996 and 1997. Presenting features were as follows: men, 62.5%; mean age at starting dialysis, 57 +/- 1 year; and mean serum creatinine level, 7.3 +/- 0.2 mg/dl. To find any clinical characteristics in the population, we divided patients into three groups according to age, as follows: Young age group (<40 years old: 12 patients), Senior age group (>65 years: 32 patients) and Middle age group: 76 patients (>40 and <65 years). The Young age group, (mean age: 36 +/- 1 years) had lower serum creatinine levels (6.1 +/- 0.4 mg/dl) (p < 0.05) and greater cardio-thoracic ratio (61.1 +/- 1.3%) (p < 0.05), obtained from the chest X-ray film, than the other two groups. There were no significant differences between the Middle age group (59 +/- 1 year) and the Senior age group (72 +/- 1 year) in the levels of serum creatinine and cardio-thoracic ratio. To further analyze the clinical characteristics, the other 113 patients in 1998 and 1999 who were matched with the Middle age group in the former study, were retrospectively analyzed. The mean age was 61 +/- 2 years, and the proportion of men was 54% (62/113). The percentage of changes in body weights were as follows: 9.5 +/- 2.8% (p < 0.05) from teens to 20s and 19.2 +/- 3.2% (p < 0.05) from teens to 30s in men. The percentage of changes in body weight in women were as follows: 9.6 +/- 2.1% (p < 0.05) from teens to 30s and 18.6 +/- 2.4% (p < 0.05) from teens to 40s. The age at the start of dialysis therapy was 54 +/- 2 years old in men and 59 +/- 3 years in women. There was a significant difference (p < 0.05) between men and women. In summary, the study suggests that young patients with diabetic nephropathy received dialysis therapy because of hypervolemic symptoms compared to older patients, and that renal deterioration progressed more rapidly in male subjects than in female subjects with diabetic nephropathy. These differences should be borne in mind in clinical practice.