Modest Salt Reduction Lowers Blood Pressure and Albumin Excretion in Impaired Glucose Tolerance and Type 2 Diabetes Mellitus

Abstract

Abstract-The role of salt restriction in patients with impaired glucose tolerance and diabetes mellitus is controversial, with a lack of well controlled, longer term, modest salt reduction trials in this group of patients, in spite of the marked increase in cardiovascular risk. We carried out a 12-week randomized double-blind, crossover trial of salt restriction with salt or placebo tablets, each for 6 weeks, in 46 individuals with diet-controlled type 2 diabetes mellitus or impaired glucose tolerance and untreated normal or high normal blood pressure (BP). From salt to placebo, 24-hour urinary sodium was reduced by 49±9 mmol (2.9 g salt). This reduction in salt intake led to fall in clinic BP from 136/81±2/1 mm Hg to 131/80±2/1 mm Hg, (systolic BP; P<0.01). Mean ambulatory 24-hour BP was reduced by 3/2±1/1 mm Hg (systolic BP, P<0.01 and diastolic BP, P<0.05), and albumin/creatinine ratio was reduced from 0.73 mg/mmol (0.5-1.5) to 0.64 mg/mmol (0.3-1.1; P<0.05). There was no significant change in fasting glucose, hemoglobin A1c, or insulin sensitivity. These results demonstrate that a modest reduction in salt intake, to approximately the amount recommended in public health guidelines, leads to significant and clinically relevant falls in BP in individuals who are early on in the progression of diabetes mellitus with normal or mildly raised BP. The reduction in urinary albumin excretion may carry additional benefits in reducing cardiovascular disease above the effects on BP. Study DesignAfter 4 weeks of participant acclimatization, participants entered into a randomized double-blind crossover study (Figure 1). Baseline measurements were taken while on participants' usual diet. Subsequently, participants were given detailed dietary advice by trained nurses to reduce salt intake to ≈5 g/d (90 mmol/d). Participants were advised not to add salt at the table or during cooking. Nurses identified food with high-salt content and advised them on low-salt alternatives. Where appropriate, the individual who prepared the food in the household was also seen. Salt-free bread was provided when required. Advice was reinforced at each visit for the duration of the study. After 2 weeks on the reduced salt diet, participants entered the randomized, double-blind crossover trial of salt versus placebo and remained on the reduced salt diet throughout the whole study. Randomization, using computer-generated random number sequences, was provided by an independent company, Healthspan Group Ltd who provided salt tablets and matching placebo tablets and had no other role in the running of the study. Participants received either 9 tablets of salt, each tablet containing 10 mmol, daily for 6 weeks or 9 matched placebo tablets, crossing over at the end of the 6-week period to take the opposite tablet for a further 6 weeks ( Figure 1). All participants and research staff were blinded to treatment allocation. MeasurementsMeasurements were performed at baseline and at the end of each 6-week study period. BP was measured by trained research nurs...

More evidence that salt increases blood pressure and risk of kidney disease from the Science of Salt: A regularly updated systematic review of salt and health outcomes (April–July 2016)

“…These studies are summarized in Table . The outcomes examined were diverse: one study assessed mortality outcomes (category I), two studies assessed morbidity outcomes (category II), two studies assessed outcomes related to symptoms/quality of life/functional status (category III), six studies assessed BP outcomes (category IV), seven studies assessed other clinically relevant surrogate outcomes (category V), and 10 studies assessed physiologic outcomes (category VI) …”

Dietary Sodium Intake in Patients with Type 2 Diabetes Mellitus

“…These results suggest that physicians should generally be cautious when recommending a daily sodium intake of 1,500 mg/day. Recently, Suckling et al [17] reported a modest reduction in dietary sodium intake in patients with T2DM in accordance with WHO guidelines, resulting in a reduction of blood pressure and albuminuria without changing the fasting glucose and glycosylated hemoglobin levels. Although additional studies are needed to clarify this debate, these findings support the practice of physicians reducing dietary sodium intake to a recommended level in diabetics.…”

Excessive consumption of salt and hypertension: Implications for public health / Consumo excesivo de sal e hipertensión arterial: Implicaciones para la salud pública

“…2016). Estos resultados muestran que un control dieté-tico completo, implementado por un especialista, junto con una forma de vida saludable, consigue un mejor efecto reductor de la TA y simpaticolítico (Beckmann et al, 1995; ESH/ESC Task Force for the Management of Arterial Hypertension, 2013; Rees et al, 2013;Suckling et al, 2016). Por tanto, para obtener mejores resultados en el control y la prevención de la HTA y sus complicaciones es trascendental trabajar en la promoción de la salud e informar a la población sobre la relación entre el CNS y el riesgo cardiovascular.…”