糖尿病性腎症を予防・治療するための食事性食塩摂取量の変更
Abstract
Background
There is strong evidence that our current consumption of salt is a major factor for increased blood pressure (BP) and a modest reduction in salt intake lowers BP whether BP levels are normal or raised. Tight control of BP in diabetics lowers the risk of strokes, heart attacks and heart failure and slows the progression of diabetic kidney disease (DKD). Currently there is no consensus in restricting salt intake in diabetic patients.
Objectives
To evaluate the effect of altered salt intake on BP and markers of cardiovascular disease and DKD.
Search methods
In January 2010, we searched the Cochrane Renal Group's Specialised Register, CENTRAL (in The Cochrane Library), MEDLINE (from 1966) and EMBASE (from 1980) to identify appropriate articles.
Selection criteria
We included all randomised controlled trials of salt reduction in individuals with type 1 and type 2 diabetes.
Data collection and analysis
Two authors independently assessed studies and resolved differences by discussion with a third independent author. We calculated mean effect sizes using both the fixed‐effect and random‐effects models.
Main results
Thirteen studies (254 individuals) met our inclusion criteria. These included 75 individuals with type 1 diabetes and 158 individuals with type 2 diabetes. The median reduction in urinary sodium was 203 mmol/24 h (11.9 g/day) in type 1 diabetes and 125 mmol/24 h (7.3 g/day) in type 2 diabetes. The median duration of salt restriction was one week in both type 1 and type 2 diabetes. BP was reduced in both type 1 and type 2 diabetes. In type 1 diabetes (56 individuals), salt restriction reduced BP by ‐7.11/‐3.13 mm Hg (systolic/diastolic); 95% CI: systolic BP (SBP) ‐9.13 to ‐5.10; diastolic BP (DBP) ‐4.28 to ‐1.98). In type 2 diabetes (56 individuals), salt restriction reduced BP by ‐6.90/‐2.87 mm Hg (95% CI: SBP ‐9.84 to ‐3.95; DBP ‐4.39 to ‐1.35). There was a greater reduction in BP in normotensive patients, possibly due to a larger decrease in salt intake in this group.
Authors' conclusions
Although the studies are not extensive, this meta‐analysis shows a large fall in BP with salt restriction, similar to that of single drug therapy. All diabetics should consider reducing salt intake at least to less than 5‐6 g/day in keeping with current recommendations for the general population and may consider lowering salt intake to lower levels, although further studies are needed.
PICO
Plain language summary
食塩摂取量の変更は糖尿病性腎症の予防と治療に効果があるか？
血圧（blood pressure：BP）が標準値であっても高値であっても、現在の食塩摂取量は血圧上昇の主要因であるという強固なエビデンスがある。糖尿病は高血圧発症の可能性を高め、それにより脳卒中や心発作のリスクが上昇し、糖尿病性腎症の進行を加速する。このレビューでは、1型および2型糖尿病254例が登録された13件の試験が見つかった。食塩摂取量を8.5 g/日減量すると、血圧が7/3 mm Hg低下する。公衆衛生ガイドラインは、食塩摂取量を5～6 g/日未満にすることを 推奨している。糖尿病患者は、食事中の塩分量をこのレベルまで低減することによってベネフィットが得られるだろう。
