From the Guidelines
Low A1C levels can be caused by several factors, including conditions that affect red blood cell lifespan or hemoglobin structure, certain medications, increased red blood cell turnover, pregnancy, frequent hypoglycemic episodes, aggressive glucose management, and genetic factors affecting hemoglobin structure. According to the American College of Physicians guidance statement 1, conditions like anemia, liver disease, kidney failure, or hemoglobin variants can artificially lower A1C readings. Certain medications, including aspirin in high doses, vitamin C and E supplements, and some HIV medications, can also decrease A1C levels. Increased red blood cell turnover from conditions such as hemolytic anemia, recent blood loss, or blood transfusions will lower A1C by reducing the time glucose has to attach to hemoglobin. Pregnancy can cause lower A1C due to increased red blood cell production. In people with diabetes, low A1C might indicate frequent hypoglycemic episodes or aggressive glucose management, as noted in the guidance statement 1. Genetic factors affecting hemoglobin structure can also lead to falsely low readings.
Some key points to consider:
- Conditions that affect red blood cell lifespan or hemoglobin structure can lower A1C readings, as discussed in the guidance statement 1
- Certain medications can decrease A1C levels, including aspirin, vitamin C and E supplements, and some HIV medications
- Increased red blood cell turnover can lower A1C by reducing the time glucose has to attach to hemoglobin
- Pregnancy can cause lower A1C due to increased red blood cell production
- Frequent hypoglycemic episodes or aggressive glucose management can lead to low A1C in people with diabetes, as noted in the guidance statement 1
- Genetic factors affecting hemoglobin structure can lead to falsely low A1C readings
If you have an unexpectedly low A1C, it's essential to consult with a healthcare provider to determine the cause, as it may require additional testing such as fructosamine or glycated albumin tests to accurately assess your glucose control, as recommended by the American College of Physicians guidance statement 1.
From the Research
Factors Contributing to Low A1C
Several factors can contribute to low A1C levels, including:
- Dietary changes, such as a low-carbohydrate diet or a low-fat, high-carbohydrate, high-fiber diet 2, 3, 4, 5
- Increased physical activity or exercise 6, 4
- Weight loss, particularly when combined with dietary changes 3, 6, 4, 5
- Medications, such as metformin, sulfonylurea, or insulin 2
- Lifestyle modifications, including individualized and group-based activities 3
Dietary Interventions
Dietary interventions have been shown to be effective in improving glycemic control and reducing A1C levels. These interventions include:
- Low-carbohydrate diets, which have been shown to lead to greater weight loss and better glucose homeostasis than exercise 4
- Low-fat, high-carbohydrate, high-fiber diets, which have been shown to improve glycemic control in patients with type 2 diabetes 2
- Mediterranean dietary patterns, which have been shown to be effective in preventing type 2 diabetes and improving glycemic control 6
Lifestyle Modifications
Lifestyle modifications, including increased physical activity and weight loss, have also been shown to be effective in improving glycemic control and reducing A1C levels. These modifications include: