Effect of sodium intake on blood pressure and albuminuria in Type 2 diabetic patients: the role of insulin resistance

Abstract

Aims/hypothesis. This study was done to measure the effect of Na + intake on blood pressure and albuminuria, in relation with insulin sensitivity and kidney haemodynamics, in Type 2 diabetic patients with and without microalbuminuria. Methods. Type 2 diabetic patients, 20 with microalbuminuria, 21 without, spent two consecutive 7-day periods, one on a high (250 mmol), the other on a low-Na + (20 mmol) diet. Body weight, 24-h blood pressure and albuminuria were measured at the end of each period. At the end of high-Na + diet insulin sensitivity (euglycaemic insulin clamp; 2 mU·kg −1 ·min −1 ) and kidney haemodynamics were measured in nine patients from each group. Results. Switching from low to high-Na + diet resulted in an increase in blood pressure (7.4±4.7 mmHg; p<0.001), body weight (1.9±0.4 kg; p<0.05) and albuminuria [from 80 (31-183) µg/min to 101 (27-965) µg/min; p<0.01) in patients with microalbuminuria. No changes occurred in patients without microalbuminuria. Patients with microalbuminuria also had greater intraglomerular pressure (44±1 mmHg vs 36±1; p<0.001), calculated from glomerular filtration rate, renal plasma flow, plasma protein concentration and the relationship between pressure and natriuresis. In these patients insulin sensitivity was lower (5.16± 49 vs 7.36±0.63 mg·kg −1 ·min −1 ; p=0.007). Urinary albumin excretion (r=0.40; p=0.009) and insulin sensitivity (r=−0.59; p=0.01) were correlated with intraglomerular pressure. Conclusion/interpretation. High salt intake increases blood pressure and albuminuria in Type 2 diabetic patients with microalbuminuria. These responses are associated with insulin resistance and increased glomerular pressure. Insulin resistance could contribute to greater salt sensitivity, increased glomerular pressure and albuminuria. [Diabetologia (2004) 47:300-303]

Increased Urinary Albumin Excretion, Insulin Resistance, and Related Cardiovascular Risk Factors in Patients With Type 2 Diabetes

“…First, it might be based on compensatory hyperinsulinemia characterizing insulin resistance, which may stimulate renal sodium reabsorption, leading to volume expansion, increased adrenergic activity, and hypertension (24 -25). Worth noting, insulin resistance could contribute to greater salt sensitivity, increased glomerular pressure, and increased UAE, as recently described in type 2 diabetic patients with microalbuminuria put on a high-salt diet (26). Thus, although in our present series a correlation between insulin resistance and blood pressure was not detectable, likely because of the ongoing antihypertensive treatment, one could speculate that the difference in blood pressure level before treatment was started may have played a significant role in determining the association between UAE and insulin resistance.…”

Meta-Analysis of the Effect of Dietary Sodium Restriction with or without Concomitant Renin-Angiotensin-Aldosterone System–Inhibiting Treatment on Albuminuria

“…These corresponded to 12 studies, of which, in the studies by Houlihan et al (12,28) and McMahon and colleagues (30,31), the effects of sodium restriction on UAE and ACR were reported in separate articles, and both were considered for the meta-analysis. Because one of 12 studies reported the outcomes in a way not suitable to our analytic approach (22), only 11 studies (corresponding to 13 articles) were included in this report (12)(13)(14)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32). As shown in Table 1, the meta-analysis involved 516 men and women overall from four countries.…”

“…The participants were healthy individuals, patients with hypertension, patients with type 1 or 2 diabetes, and/or patients with normo-or microalbuminuria, established proteinuria, or a combination thereof. Most studies provided multiple cohorts (for a total of 20), including different categories of patients (25)(26)(27) or patients on different pharmacologic treatments according to a parallel arm or cross-over design (12)(13)(14)28,29,32).…”

“…The length of intervention ranged from 1 to 6 weeks. The evaluation of the risk of bias level indicated that seven studies were at low risk of bias (14,23,24,27,(29)(30)(31)(32) and that four studies were at high risk of bias (12,13,25,26) (Table 2). External funding sources were declared in all but two studies (Supplemental Table 3).…”

Metabolic Syndrome Associated Kidney Damage

“…Insulin resistance could contribute to greater salt sensitivity, increased glomerular pressure and albuminuria. [11] Insulin resistance increase the renal damage by the plasminogen activator inhibitor 1…”