Glutamine supplementation for blood glucose control

This study examined the use of glutamine and sitagliptin as a treatment for type 2 diabetes mellitus.

Glucagon-like peptide-1 (GLP-1) is a hormone that is produced and released following the intake of food. GLP-1 increases insulin production, the hormone responsible for breaking down the glucose (sugar) taken in from food. GLP-1 action is slowed by another hormone, dipeptidyl peptidase (DPP-4).

Treatments that increase GLP-1 release (called GLP-1 agonists) and decrease DPP-4 (called DPP-4 inhibitors) are used in patients with type 2 diabetes mellitus, as they increase insulin levels and also lead to a feeling of fullness, helping to decrease food intake. Glutamine is an amino acid (a building block of protein) that stimulates the release of GLP-1. 

The current study examined whether treatment with both glutamine and sitagliptin (Januvia, a DPP-4 inhibitor) was effective at lowering the average blood glucose levels in patients with type 2 diabetes who were already being treated with metformin (Glucophage; decreases glucose production by the liver).

In this study, 13 patients were randomly assigned to one of two treatment groups. One group received glutamine and sitagliptin for 4 weeks, followed by 4 weeks without treatment, then 4 weeks of glutamine and a placebo (a substance with no effect on the body used as a comparison). The other group had the treatment schedule switched, with glutamine plus placebo for the first 4 weeks, and glutamine plus sitagliptin for the last 4 weeks. HbA1c (average blood glucose levels over the previous 3 months) and fructosamine (average blood glucose levels over the previous 2-3 weeks) levels were measured at the start of the study and at the end of both treatment periods, as was basic blood chemistry (for example, levels of white and red blood cells, levels of proteins).

HbA1c and fructosamine levels decreased following treatment with glutamine. Levels of GLP-1 measured at fasting (following a period without food or drink) increased by an average of 2.0 pmol/L following glutamine plus placebo, and an average of 2.1 pmol/L following glutamine plus sitagliptin. This increase did not depend on the order of the treatments.

White blood cell and red blood cell counts decreased, as did the levels of several proteins in the blood (decreased protein in the blood can affect the structure of the blood cells, leaving them more likely to leak fluid into body tissue). Body weight and electrolytes (minerals in the blood that carry an electric charge, which can affect muscle function and acidity of the blood) did not change.

This study concluded that glutamine, either with or without sitagliptin, decreased HbA1c and fructosamine levels in patients with type 2 diabetes, but also led to decreased blood cell and blood protein levels.

This was a small study, with a small number of subjects. This treatment should be repeated with a larger number of participants.