Snacking your way to lower glucose? Pistachio consumption in prediabetes

This study examined the effect of pistachio consumption on glucose and insulin levels in patients with prediabetes.

Patients with prediabetes have blood glucose (sugar) levels that are higher than normal, but not high enough to be considered type 2 diabetes. It is estimated that between 3.5% and 7.0% of untreated prediabetes patients progress to type 2 diabetes each year. As type 2 diabetes is associated with many complications, including cardiovascular disease, it is important to slow that progression. For many patients, a combination of improved diet and exercise, along with anti-diabetic drugs, can reduce the risk of type 2 diabetes and cardiovascular disease.

Adding nuts (such as almonds, walnuts, or pistachios) to the diet has been shown to decrease the risk of coronary artery disease and to lower cholesterol levels. Eating pistachios also improved blood glucose levels in healthy subjects, but did not have an effect on insulin (the hormone needed to break down glucose) levels. The effects of nut consumption on type 2 diabetes have not been as clear. It is not known what effect nut consumption has on prediabetic patients.

This 8-month study examined the effect of adding pistachios to the daily diet of 49 prediabetic patients. For 4 months each patient followed a pistachio-supplemented diet (2 ounces of pistachios per day), along with a diet set by the study. During the other 4 months each patient followed the same diet without the addition of pistachios. Fasting glucose and insulin levels (levels following a period without food or drink), HbA1c (average blood glucose over 3 months), glucagon-like peptide-1 (GLP-1, a hormone that increases insulin release in response to glucose), insulin resistance (how easily the body used the insulin) and amount of insulin secretion were measured.

During the pistachio supplementation diet, fasting glucose levels decrease by 5.17 mg/dL and fasting insulin levels decreased by 2.04 mU/mL. In comparison, during the non-supplemented diet, fasting glucose levels increased by 6.72 mg/dL and fasting insulin levels increased by 2.51 mU/mL. Insulin resistance also decreased during pistachio supplementation, and increased without it. GLP-1 levels increased by 4.09 pg/mL with pistachio supplementation, and decrease by 0.59 pg/mL without. There were no significant changes in HbA1c or insulin secretion between the two diets.

This study concluded that daily pistachio consumption led to decreased fasting blood glucose and insulin levels, as well as decreased insulin resistance in patients with prediabetes.

This study was funded by the American Pistachio Growers.