Evaluating the long-term effects of a moderate low-carbohydrate diet on blood glucose control and liver function in patients with type 2 diabetes

This study evaluated the long-term effects of a moderate low-carbohydrate diet (LCD) on blood glucose control and liver function in patients with type 2 diabetes (T2D). The data showed that patients on a moderate LCD diet showed better blood glucose control and liver function over the long term than patients on a traditional diabetic diet (TDD).

T2D is a condition in which patients have high blood sugar (glucose) levels (hyperglycemia). Long-term high blood glucose levels can damage blood vessels, nerves, and entire organs. This can lead to complications such as heart attack, high blood pressure, stroke, kidney and liver disease, loss of sight, and nerve damage. Diet plays an important role in the management of T2D. A healthy diet can help in controlling blood glucose levels, managing weight, and reducing complications.

Patients with T2D are usually recommended a lower than usual level of carbohydrates (glucides or sugars) per day compared to a non-diabetic person. This is called a traditional diabetic diet (TDD). A previous study showed that 90g/day of carbohydrates (LCD) improved average blood glucose levels, lowered blood pressure, and decreased body weight in patients with T2D. However, the long-term effects of a moderate LCD on blood glucose control and liver function in patients with T2D are unknown.

This study involved 71 patients with T2D. Patients were randomly assigned into 2 groups. Group 1 included 35 patients who were on a TDD. Group 2 included 36 patients who were on a 90g/day LCD. Patients were followed up for up to 1 year after the study finished to evaluate their overall glucose levels and liver function.

Before the study, patients in both groups were consuming around 235-240g of carbohydrates/day. After 18 months, patients in group 2 consumed a significantly lower amount of daily carbohydrates (88g/day) than patients in group 1 (151g/day). After 30 months, group 2 still consumed significantly fewer carbohydrates per day (131g/day) compared to group 1 (195g/day).

The glycosylated hemoglobin (average blood glucose over the last 3 months; HbA1c) levels were significantly lower in group 2 at both 18 months (6.87% vs 7.6%) and at 30 months (7.18% vs 7.69%) compared to group 1. The two-hour blood glucose, blood alanine aminotransferase (a measure of liver function), and medication effect score were also significantly lower for group 2 than those in group 1 at both evaluation times.

This study concluded that patients on a moderate LCD diet showed better blood glucose control and liver function over the long term than patients on a traditional diabetic diet.

The sample size was very small. This study only included patients treated at a single medical institution in Taiwan. The diagnosis of T2D was made by clinicians based on patients’ blood glucose levels and HbA1c, no other diagnostic tests were performed. The patients were not evaluated for their physical activity.

Discuss with your doctor if a moderately low carbohydrate diet would be optimal for your situation.