Before a blood cholesterol test, doctors typically advise that a person fasts for several hours to get the most accurate results. However, a new study shows that in the case of people with diabetes, this approach could do more harm than good.

People with diabetes tend to have higher levels of low-density lipoprotein cholesterol or "bad cholesterol." This can lead to the excessive buildup of fat in the arteries. For this reason, doctors may 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 not skew its results. However, increasingly, studies are suggesting that this step may not be necessary and that it may actually cause harm in some cases.

New research led by specialists at Michigan State University in East Lansing reports that fasting before a blood cholesterol test can give rise to low blood sugar, or hypoglycemia, in individuals with diabetes who take insulin or sulfonylurea (a drug to manage type 2 diabetes).

The team worked with 525 people with diabetes who attended one of two endocrinology clinics in Michigan. The scientists asked them to fill in a two-page survey and following an analysis of this information, the researchers 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. FEEHD can lead to life-threatening accidents if the person in question is driving ("en route") to the clinic where the blood test will take place.

"Hypoglycemia is an overlooked problem that we see from time-to-time in patients with diabetes who show up for lab tests after skipping breakfast," explains study author Saleh Aldasouqi. "Our new motto is 'Feed not FEEHD,'" he goes on, "to remind patients of this danger and get them to eat." Aldasouqi also points out that 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 laboratory.

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