High blood sugar is usually not a good idea to donate blood, and it is not recommended for people with high blood sugar because of the poor resistance of the patients themselves. Donating blood is a noble thing to do, but patients suffering from endocrine diseases or metabolic disorders are usually not recommended to donate blood. Patients with chronically high blood glucose may have low immunity and are prone to infections, so blood donation is not recommended. In addition, patients with infectious diseases such as Hepatitis B, Hepatitis C, syphilis and AIDS are also unable to participate in blood donation. Patients with high blood glucose should improve their diet, exercise properly and take treatment under the guidance of a doctor, who can be consulted for details about blood donation.