was essen vor blutabnahme — what can you do yourself?

Before a blood draw, the most important thing you can do yourself is to follow fasting instructions. For most routine blood tests (e.g., fasting glucose, lipid panel), a fast of 8–12 hours is recommended, during which only water is allowed. Fatty or sugary meals shortly before the draw can skew results (e.g., triglycerides, glucose). Coffee, tea, or sugary drinks should also be avoided as they affect metabolism. Some tests (e.g., HbA1c) are less dependent on fasting, but to be safe, follow the specific instructions from your doctor or lab. If you take medications, check beforehand whether they can be taken in the morning. Drinking enough plain water (still) makes vein puncture easier. In summary: stay fasting, drink only water, no food, no coffee, no nicotine. These measures are standard medical practice; evidence is practice-based rather than from randomized trials. When in doubt, always contact the lab.