Astragalus and diabetes: kidney protection

Astragalus (Astragalus membranaceus), a medicinal plant used for millennia in traditional Chinese medicine, is known for its tonic and immunostimulating properties. In the context of diabetes, a chronic disease affecting millions of people worldwide, astragalus is generating increasing interest for its potential protective effects on organs, particularly the kidneys. Diabetes, especially type 2, is a major cause of diabetic nephropathy (DN), a kidney complication that can lead to end-stage renal disease. This article explores the scientific evidence on the role of astragalus in kidney protection in diabetic patients, based on preclinical and clinical studies. We will examine the mechanisms involved, the observed benefits, and precautions for use.

What is astragalus?

Astragalus is a herbaceous plant native to Asia, whose root is primarily used in herbal medicine. It contains active compounds such as polysaccharides (APS), saponins (like astragaloside IV), and flavonoids, which give the plant anti-inflammatory, antioxidant, and immunomodulatory properties. In traditional medicine, it is prescribed to strengthen “Qi” (vital energy) and treat conditions related to immune deficiency or chronic diseases such as diabetes. Modern research has begun to validate these uses, focusing on its hypoglycemic and organ-protective effects.

In diabetes, chronic hyperglycemia damages blood vessels and tissues, promoting complications such as nephrotic syndrome (NS). NS is characterized by albuminuria (the presence of protein in the urine), elevated serum creatinine (SCr) and blood urea nitrogen (BUN) levels, as well as a progressive deterioration of kidney function. Astragalus may play a role in mitigating this damage through several metabolic pathways.

General Effects of Astragalus on Diabetes

Before discussing kidney protection, it is worth noting that astragalus has beneficial effects on glycemic control. Studies show that it can reduce fasting blood glucose and improve glucose tolerance. For example, astragalus polysaccharides (APS) work by increasing insulin sensitivity and modulating signaling pathways involved in carbohydrate metabolism. This lays the groundwork for reducing diabetic complications, including renal complications, as better blood glucose control is essential to prevent the progression of diabetic nephropathy (DN).

Mechanisms of Renal Protection of Astragalus in Diabetes

• Preclinical research, primarily on animal models of diabetes (rats or mice induced by streptozotocin or a high-fat diet), demonstrates that astragalus protects the kidneys through several mechanisms: Reduction of Oxidative Stress and Inflammation: Diabetes induces an excess of free radicals that damage kidney cells. Astragalus, rich in antioxidants, increases the expression of enzymes such as superoxide dismutase (SOD) and decreases inflammatory markers such as TNF-α and IL-6.
• Inhibition of Renal Fibrosis Neurodystrophy (ND) involves an accumulation of extracellular matrix leading to fibrosis. Astragalus decreases the expression of profibrotic factors such as TGF-β1, CTGF, and collagen IV, while increasing antifibrotic markers like BMP-7.
• Promotion of autophagy and protection of podocytes: Podocytes, key cells of the renal glomerulus, are damaged in ND, leading to proteinuria. Astragalus activates various pathways that promote autophagy and reduce glomerular hypertrophy.
• Improvement of overall renal function: In ND models, astragalus reduces urinary albumin excretion, improves creatinine clearance (CCr), and attenuates histological changes such as glomerular hypertrophy. These mechanisms are supported by meta-analyses that synthesize data from multiple animal studies, showing consistent effects on renal markers. Clinical Evidence

While animal studies are promising, clinical data are more limited but encouraging. Meta-analyses of clinical trials have shown that injecting or taking astragalus improves kidney function in patients with ND, reducing BUN, SCr, and protein in the urine, and increasing CCr.

A recent randomized clinical trial in patients with type 2 diabetes and chronic kidney disease found that adding astragalus to standard treatment slowed the decline in glomerular filtration rate (GFR). Furthermore, combinations with other herbs also improved kidney function in diabetic patients. These results suggest that astragalus could be a useful adjunct to conventional treatments such as ACE inhibitors or ARBs.

However, clinical trials are often small-scale and conducted in China, highlighting the need for more international research to confirm these effects.

Precautions and Side Effects

Although generally well-tolerated, astragalus can interact with immunosuppressant or antidiabetic medications, potentially increasing their effects. Rare side effects include gastrointestinal disturbances or allergic reactions. It is contraindicated in pregnant or breastfeeding women without medical advice. Always consult a healthcare professional before incorporating astragalus into a therapeutic regimen, especially in cases of advanced diabetes or diabetic nephropathy (DN).

Conclusion

Astragalus, through its active compounds such as APS (alpha-suppressant polysaccharides), offers promising renal protection in diabetes by mitigating oxidative stress, inflammation, and fibrosis, and by promoting autophagy. Preclinical and clinical studies support its role in reducing markers of renal dysfunction and slowing the progression of DN. Although more research is needed to establish standardized protocols, astragalus represents a natural complementary option for managing diabetes and its renal complications. By adopting an integrative approach, combining herbal medicine and conventional medicine, patients could benefit from an improved quality of life.