Against the background of the high comorbidity of diabetes and cardiovascular diseases, the medical role of salt is gradually shifting from a simple risk factor for blood pressure to a more complex and sophisticated hub for metabolic regulation.
Recently, at the Annual Meeting of the Chinese Diabetes Society (CDS), Professor Zhu Zhiming from the Department of Hypertension and Endocrinology, Daping Hospital, Army Medical University, delivered a systematic and in-depth presentation on the relationship between salt intake and diabetes.
Salt and sugar are two essential nutrients for life and daily living, but their excessive intake is closely associated with the epidemic of modern chronic diseases. China is one of the earliest countries in the world to recognize that a high-salt diet can cause diseases. As early as 2000 BC, Huangdi Neijing recorded that “saltiness leads to taut pulse.”
As the oldest and most widely used seasoning, salt (NaCl) not only has traditional applications such as sterilization, preservation, and wound debridement, but also plays an irreplaceable physiological role in maintaining cellular and plasma osmotic pressure, participating in glucose and protein metabolism, and sustaining nerve excitability.
However, physiologically, the daily physiological requirement of salt for humans is about 2 g, while the average intake among Chinese residents has long exceeded 10 g per day. Excessive salt intake has become a major public health issue.
Numerous studies have confirmed a clear and consistent positive correlation between blood pressure and salt intake. A high-salt diet significantly elevates systolic and diastolic blood pressure, and salt-reduction interventions can markedly reduce the risk of cardiovascular events. More than 50% of Chinese individuals have salt-sensitive hypertension. High salt intake can increase systolic blood pressure by about 4 mmHg and diastolic blood pressure by about 2 mmHg. Reducing daily sodium intake by 2.0–2.3 g can lower cardiovascular risk by approximately 20%.
Meanwhile, a high-sugar diet is also closely linked to elevated blood pressure: high sugar intake significantly increases systolic blood pressure (by ~6.9 mmHg) and diastolic blood pressure (by ~5.6 mmHg), suggesting that sugar and salt exert a synergistic amplifying effect on blood pressure regulation.
Comorbidity between diabetes and hypertension is highly prevalent. Epidemiological data show that about 60% of patients with type 2 diabetes have hypertension, and approximately one-quarter of hypertensive patients also have diabetes.
In a study of patients with type 1 diabetes, dietary salt intake was independently associated with the risk of all-cause mortality and end-stage renal disease (ESRD). During a median follow-up of 10 years, 217 patients (7.7%) died. Urinary sodium excretion showed a nonlinear relationship with all-cause mortality: survival rates were lower in both the highest and lowest excretion groups, independent of age, sex, diabetes duration, severity of chronic kidney disease (CKD), cardiovascular disease, and systolic blood pressure.
During follow-up, 126 patients (4.5%) progressed to ESRD. Urinary sodium excretion was inversely associated with ESRD risk, with the lowest excretion group having the highest ESRD incidence. Although causality was not proven, these findings support a cautious approach before universal salt restriction is implemented.
In patients with type 2 diabetes, a paradox was observed between lower 24-hour urinary sodium excretion and increased all-cause and cardiovascular mortality. Each 100 mmol increase in 24-hour urinary sodium was associated with a 28% decrease in all-cause mortality. This paradox suggests that overly strict salt restriction may not be universally safe.
Overall, both salt and sugar intake are closely related to hypertension, but no unified conclusion has been reached regarding the relationship between salt intake and cardio-renal and vascular events in diabetes, indicating that this field still has important research value and clinical uncertainty.