Welcome to e health forum.
The description of pain in the lower back, radiating to the thighs, legs and the foot, could be due to conditions like diabetic neuropathy, Sciatica, or peripheral neuropathy.
Since you have mentioned that your mother is diabetic, the condition is probably due to diabetic neuropathy.
Diabetic neuropathy is a common complication of diabetes, in which nerves are damaged as a result of high blood sugar levels (hyperglycemia).
People with diabetes commonly develop temporary or permanent damage to nerve tissue. Nerve injuries are caused by decreased blood flow and high blood sugar levels, and are more likely to develop if blood sugar levels are not well controlled.
Some people with diabetes will not develop nerve damage, while others may develop this condition early. On average, symptoms begin 10 to 20 years after the diabetes diagnosis. Approximately 50% of people with diabetes will eventually develop nerve damage.
The severity of diabetic neuropathy depends on the age, duration of diabetes, current glycemic control, the degree the nerves and tissues are affected and the current treatment.
The goals of treating diabetic neuropathy are to prevent the disease from getting worse and to reduce the symptoms of the disease.
Tight control of blood sugar (glucose) is important to prevent symptoms and problems from getting worse.
Medications may be used to reduce the symptoms in the feet, legs, and arms. These medications include: Amitriptyline, Doxepin, duloxetine, Gabapentin, Pregabalin, and valproate are used to treat the painful symptoms.
Capsaicin can be used topically to reduce pain.
In case one of the drug is not helpful over a period of time, your doctor can try a better one after due consideration. Every individual will respond to a different drug depending on the individual situation. But most newer drugs like gabapentin and duloxetine are always helpful to control the pain.
You mother might need to consult her doctor for a proper physical examination and proper treatment.
I hope this helps.