Why is the blood glucose level higher in fingerstick blood than in venous blood?

Generally speaking, the reasons why fingertip blood glucose levels are higher than venous blood glucose levels include differences in blood composition, differences in testing time, abnormal pancreatic function, adrenal cortical insufficiency, and diabetes mellitus. Prompt medical consultation is needed, and treatment should follow medical advice. Details are as follows:

1. Differences in blood composition: Fingertip glucose measurement assesses the glucose content in capillary whole blood, whereas venous glucose testing measures the glucose level in plasma or serum from the elbow vein. Whole blood contains components such as red blood cells, which absorb some glucose, leading to relatively higher fingertip glucose readings. No specific treatment is required, but regular glucose monitoring is recommended to understand glucose trends.

2. Differences in testing time: Fingertip glucose testing is typically used for routine glucose monitoring, while venous glucose testing is more commonly used for clinical diagnosis in hospitals. Due to differences in testing times and conditions, there may be discrepancies between the two measurements. It is recommended to compare results within the same timeframe—for example, both measurements taken two hours after a meal—to reduce the impact of testing time differences on results.

3. Abnormal pancreatic function: Abnormal pancreatic function refers to insufficient insulin secretion by pancreatic β cells or excessive glucagon secretion by α cells, which may be related to genetic factors, environmental factors, or autoimmune responses. This can lead to unstable blood glucose levels. Under a physician's guidance, medications such as acarbose tablets, glimepiride tablets, and metformin hydrochloride tablets can be used to regulate blood glucose levels.

4. Adrenal cortical insufficiency: Adrenal cortical insufficiency leads to reduced secretion of adrenal cortical hormones, thereby affecting glucose metabolism. Adrenal cortical hormones have a blood glucose-elevating effect; when their secretion decreases, blood glucose levels may drop, and fatigue may also occur. Under a physician's guidance, medications such as hydrocortisone tablets, prednisolone acetate tablets, and methylprednisolone tablets can be used for treatment, exerting anti-inflammatory effects.

5. Diabetes: Diabetes is a chronic metabolic disorder caused by absolute or relative insulin deficiency due to impaired insulin secretion by pancreatic β cells and reduced insulin sensitivity in the body, leading to metabolic disturbances in carbohydrates, fats, and proteins. This results in persistently elevated blood glucose levels and may also be accompanied by polydipsia (excessive thirst). Under medical guidance, medications such as insulin glargine injection, insulin aspart injection, and insulin degludec injection can be used to regulate blood glucose levels.

During treatment, it is important to follow medical instructions, take medications on time, and adjust lifestyle and dietary habits to promote recovery.

References:

[1] Li Libo, Zhang Ling, et al. Analysis of Differences in Blood Glucose Test Results Between Fingertip Blood and Venous Blood [J]. China Practical Medicine, 2021.