I am diabetic for 21yrs. I hv been on insulin for 11yrs. I now feel numbness on my left foot near my limbs?

You need to be . Sure that your sugar is well controlled and under the care of an endocrinologist. You certainly do not want to get diabetic neuropathy and other complications of diabetes when you are non-compliant and poorly controlled sugar. Your other health issues are also very important. Please consult with your physician and get well. He may prescribe Lyrica (pregabalin) or Neurontin etc to help.
Pain, numbness. . When diabetics have uncontrolled blood sugars their nerves pay the price over time. They can have tingling, burning, and numbness, or even pain, and once it happens it's impossible to get normal sensation back. Some medications reduce the tingling, but not much can reverse numbness. See your doctor for an evaluation and possible oral or topical medications.
Many possibilities. Numbness can occur from various reasons. Some potential causes include vitamin deficiency, nerve damage, nerve compression, and alcohol over consumption, side effects of different medications, or as a result of different systemic medical conditions such as diabetes. Get evaluated by a professional to determine the diagnosis. Treatment is based on the diagnosis.