Doctors usually advise that people taking blood cholesterol tests should fast for several hours before the test to get the most accurate results. However, a new study shows that in the case of people with diabetes, this approach could be more harmful than good.
People with diabetes tend to have higher levels of low-density lipoprotein cholesterol, usually referred to as ‘bad cholesterol’, which could lead to a buildup of fat in the arteries. Doctors typically recommend that these people have regular blood cholesterol tests.
Current guidelines recommend that people do not eat or drink anything but water before a blood test, in order to ensure the results do not get skewed. However, new studies by researchers at Michigan State University in the US show that this fasting is not really necessary and could in many cases prove harmful.
The researchers say that fasting before a blood cholesterol test can give rise to low blood sugar, or hypoglycemia, in individuals with diabetes who take insulin or other drugs to to manage type 2 diabetes.
The team, which worked with 525 people with diabetes who attended endocrinology clinics, found that people with diabetes were more likely to experience fasting-evoked en-route hypoglycemia (FEEHD) if they had fasted before having a blood test. In FEEHD, blood sugar levels become abnormally low — under 70 milligrams per deciliter — which can cause faintness, confusion, and dizziness. This can lead to life-threatening accidents if the person in question is driving to the clinic where the blood test will take place.
If patients continue taking their diabetes medication but do not eat anything, it results in low blood sugar levels that cause them to have a hypoglycemic event while driving to or from the clinic, putting themselves and others at risk, said the team behind the study.
Also, specialists currently recognize that eating before undergoing a blood cholesterol test is unlikely to affect relevant measurements. Therefore, having a meal before going in for a test may actually be better than fasting and potentially losing consciousness on the way to the clinic.
The idea of fasting before a blood test comes from antiquated sets of guidelines from the 1970s, which specialists in Canada and most European countries no longer use. Doctors who continue to recommend fasting may want to consider revising their guidelines to better fit the needs of their patients.
Patients who receive orders for a blood cholesterol test should ask their doctors if fasting is really necessary, and if so, how they should handle their diabetes medications during the fasting period to account for the changes in their blood sugar levels.