Salt increases the risk of cardiovascular disease and renal failure in diabetics

Patients with diabetes run a higher risk of cardiovascular disease, renal failure and premature death, particularly if they have too much salt in their diet. Excessive salt intake also blocks the effect of drugs prescribed to regulate high blood pressure. These are among the results of a large-scale study of 1,177 patients with diabetic renal disease carried out by Hiddo Lambers Heerspink, clinical pharmacologist at UMCG. He is the first person to research the impact of salt intake on the long-term effects of antihypertensive drugs in patients with type 2 diabetes. Today sees the publication of his article on the subject in the scientific journal 'Kidney International'.

Patients with diabetes and kidney damage have a very high risk of cardiovascular disease, end-stage kidney failure and premature death. Protection is based on proper regulation of blood sugar levels combined with drugs that regulate the so-called renin-angiotensin-aldosterone system (RAAS).  However, short-term studies into hypertension and renal disease have shown that these drugs become less effective if the patient’s diet contains too much salt. A lack of firm data about salt intake meant that it was not known whether this also applied to patients with diabetes, and whether it had longer-term implications for the heart, kidneys and survival rate. The results of Hiddo Lambers Heerspink’s study have brought more clarity to the situation.

For the purposes of his research, Hiddo Lambers Heerspink analyzed the combined data set of two major studies in patients with diabetic kidney disease; the RENAAL/IDNT data sets. These were the studies that gave the original evidence of a protective effect of the RAAS blockade in patients with diabetes. Salt levels in the urine were recorded to ascertain the level of salt in 1,177 patients’ diets: the average amount was about 10.5 gram/day, which is far above the acceptable amount in a healthy diet (6 gram/day). An intake of 12 gram or more eradicated the protective effect of the RAAS blockade on the heart and kidneys altogether: the results for this group of patients were the same as for the control group. The effect of the RAAS blockade improved greatly with a lower salt intake (about 8 gram/day): the risk of cardiovascular disease and loss of renal function in these patients was a staggering 50% lower! 

These results quite clearly show that reducing salt intake is an essential element of protection against cardiovascular disease and progressive kidney damage for patients relying on a RAAS blockade. Furthermore, the study shows that a positive effect can be attained even if salt reduction is minimal. This is in line with recent findings from short-term studies and studies of patients with non-diabetic renal disease.  According to Hiddo Lambers Heerspink, these promising results are a good reason for focusing renewed attention on lifestyle counselling to correct the excessive use of salt among kidney patients with diabetes: based on this study, huge health benefits can be expected.