The basics

Donating blood is a selfless way to help others. Blood donations help people who need transfusions for many types of medical conditions, and you may decide to donate blood for a variety of reasons. A pint of donated blood may help up to three people. Although you’re allowed donate blood if you have diabetes, there are a few requirements that you’ll need to meet.

If you have diabetes and want to donate blood, it’s generally safe for you to do so. People with type 1 and type 2 diabetes are eligible to give blood donations. You should have your condition under control and be in otherwise good health before you donate blood.

Having your diabetes under control means that you maintain healthy blood sugar levels. This requires you to be vigilant about your diabetes on a daily basis. You need to be aware of your blood sugar levels throughout each day and make sure you eat a proper diet and exercise sufficiently. Living a healthy lifestyle will contribute to keeping your blood sugar levels in a healthy range. Your doctor may also prescribe certain medications to help manage your diabetes. These medications shouldn’t impact your ability to donate blood.

If you want to donate blood but are concerned about your diabetes, talk to your doctor before your donation. They can answer any questions you may have and help you determine whether this is the best option for you.

Health screening

Blood donation centers have a screening process that requires you to disclose any preexisting health conditions. It’s also a time where a certified Red Cross professional will evaluate you and measure your basic vital statistics, such as your temperature, pulse, and blood pressure. They will take a small blood sample (likely from a finger prick) to determine your hemoglobin levels as well.

If you have diabetes, you will need to share your condition at the screening. The person screening you may ask additional questions. You should make sure you have information about any medications you may be taking to treat your diabetes. These diabetes medications shouldn’t disqualify you from donating blood.

People who donate blood, regardless of whether they have diabetes, must also meet the following requirements:

  • be in good health in general and on the day you donate
  • weigh at least 110 pounds
  • be 16 years or older (age requirement varies by state)

You should reschedule your session if you aren’t feeling well on the day of your blood donation.

There are other health conditions and factors, such as international travel, that may prevent you from donating blood. Check with your blood donation center if you there are other considerations, health or otherwise, that may prevent you from donating.

Blood donation

The entire blood donation process takes about an hour. The time spent actually donating blood typically takes about 10 minutes. You will be seated in a comfortable chair while you donate blood. The person assisting you with the donation will sanitize your arm and insert a needle. Generally, the needle will only cause a slight amount of pain, similar to a pinch. After the needle goes in, you shouldn’t feel any pain.

Before you decide to donate blood, there are a few ways you can prepare to make sure your donation is successful. You should:

  • Drink plenty of water leading up to the donation. You should increase your water intake a few days before your scheduled donation.
  • Eat iron-rich foods or take an iron supplement one to two weeks before the donation.
  • Sleep well the night before your donation. Plan on getting eight or more hours of sleep.
  • Eat balanced meals leading up to your donation and afterward. This is especially important when you have diabetes. Maintaining a healthy diet that keeps your blood glucose levels low is key to having control of your condition.
  • Limit caffeine on donation day.
  • Bring a list of the medications you are currently taking.
  • Carry identification with you, such as your driver’s license or two other forms of identification.

After the donation, you should monitor your blood sugar level and continue to eat a healthy diet. Consider adding iron-rich foods or a supplement to your diet for 24 weeks following your donation.

In general, you should:

  • Take acetaminophen if your arm feels sore.
  • Keep your bandage on for at least four hours to avoid bruising.
  • Rest if you feel lightheaded.
  • Avoid strenuous activity for 24 hours after the donation. This includes exercise as well as other tasks.
  • Increase your fluid intake for a few days following your donation.

If you feel sick or are concerned about your health after the blood donation, contact your doctor immediately.

Donating blood is an altruistic endeavor that can directly help people. Living with well-controlled diabetes shouldn’t prevent you from donating blood on a regular basis. If your diabetes is well-controlled, you can donate once every 56 days. If you begin experiencing unusual symptoms after donating, you should consult your doctor.


Will my blood sugar run lower or higher after I donate? Why is this, and is this “normal”?

Anonymous patient


After you donate blood, your blood sugar level should not be affected and cause high or low readings. However, your HbgA1c (glycated hemoglobin, which measures your three-month blood sugar level) may be falsely lowered. The HbgA1c is thought to be lowered because of the blood loss during donation, which can lead to an acceleration of red blood count turnover. This effect is only temporary.

Alana Biggers, MD, MPHAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.