Blood Sugar Management Research

Since the 2003 FDA-approved health claim for nuts and heart disease, there has been an increase in the number of studies showing not only the positive role of nuts in reducing the risk of cardiovascular disease, but also the potential benefits of nut consumption on blood glucose, diabetes, metabolic syndrome and insulin sensitivity.

• The results from the largest randomized clinical trial to date on nuts and diabetes showed that eating about 2 ounces of nuts a day for 3 months, as a replacement for carbohydrate foods, may improve long-term blood sugar control and LDL cholesterol in people with type 2 diabetes. In this study, people snacking on pistachios experienced a significant reduction in HbA1c, a long-term marker of blood sugar control, and a significant reduction in LDL cholesterol.
[Jenkins DJA, et al. Nuts as a replacement for carbohydrates in the diabetic diet. Diabetes Care. 2011. Aug;34(8):1706-1711.]

• A 2011 paper presented two short-term studies published in the European Journal of Clinical Nutrition that examined the effects of eating pistachios on blood glucose after a meal. This study showed that pistachios added to different common carbohydrate foods, such as rice and pasta, significantly reduced the relative blood sugar response of the carbohydrate meals with which they were eaten. Pistachios eaten with a carbohydrate-rich meal lowered the blood glucose response in a dose-dependent manner, e.g., the higher the dose of pistachios, the more the blood sugar level was lowered.
[Kendall CWC, et al. The impact of pistachio intake alone or in combination with high-carbohydrate foods on post-prandial glycemia. Eur J Clin Nutr. 2011;65(6):696-702.]

• The results of an epidemiologic cohort study suggested that frequent nut and peanut butter consumption (five times per week) may be associated with a significantly lower cardiovascular disease risk in women with type 2 diabetes.
[Li TY, et al. Regular consumption of nuts is associated with a lower risk of cardiovascular disease in women with type 2 diabetes. J Nutr. 2009; 139:1333-1338.]

• Managing cardiovascular risk factors is important for reducing vascular complications in type 2 diabetes, even in individuals who have achieved glycemic control. In a study published in 2014, the researchers observed that a moderate-fat diet containing pistachios modestly improved some cardiovascular risk factors in adults with well-controlled type 2 diabetes.
[Sauder KA, et al. Pistachio Nut Consumption Modifies Systemic Hemodynamics, Increases Heart Rate Variability, and Reduces Ambulatory Blood Pressure in Well-Controlled Type 2 Diabetes: a Randomized Trial. J Am Heart Assoc. 2014;3:e000873]

Below are a handful of recent studies on pistachios and blood sugar management

Assaf-Balut C, et al. A Mediterranean diet with additional extra virgin olive oil and pistachios reduces the incidence of gestational diabetes mellitus (GDM): A randomized controlled trial: The St. Carlos GDM prevention study. PLoS One. 2017 Oct 19;12(10):e0185873. doi: 10.1371/journal.pone.0185873.

Gestational diabetes mellitus (GDM) prevalence is increasing and becoming a major public health concern. This prospective, randomized, controlled, clinical trial, compared the effect of a Mediterranean Diet supplemented with extra-virgin olive oil and pistachios (MedDiet) to a standard low fat diet (Control) on the incidence of gestational diabetes.
Women on the MedDiet had a lower incidence of GDM, lower rates of GDM that required insulin treatment, lower premature births, emergency CS and small for gestational age newborns than those on the control diet.
This study shows that a Mediterranean diet supplemented with extra-virgin olive oil and pistachios early in gestation reduces the incidence of gestational diabetes and improves several maternal and neonatal outcomes

Dreher ML. Pistachio nuts: composition and potential health benefits. Nutr Rev. 2012;70(4):234-40.

A growing number of clinical studies suggest potential health benefits of pistachio nuts. This review examined the nutrients and phytochemicals in pistachios as well as the potential health effects of these nuts.
Five published randomized clinical studies have shown that pistachios have a beneficial effect on blood lipid profiles. Emerging clinical evidence suggests that pistachios may help reduce oxidative and inflammatory stress and promote vascular health, glycemic control, appetite management, and weight control.

Ge, Sheng, et al. Effect of pistachio intake on postprandial glycemic response in pregnant woman: a randomized, controlled, cross-over study. FNCE, Oct. 2017.

A growing concern, gestational diabetes mellitus (GDM) prevalence is estimated at 9.8 – 25.5% worldwide. Elevated blood sugar during pregnancy not only impacts the mother’s health, but it may also increase the baby’s risk of developing diabetes.
This study showed pistachios may help maintain postprandial blood glucose levels while providing essential nutrients to the mother and baby during pregnancy. Sixty pregnant women were screened for having either gestational impaired glucose tolerance or gestational diabetes mellitus. In a randomized crossover study, the women consumed 42 g pistachios or 100 g whole wheat bread in a random order after fasting. These amounts of pistachios and whole wheat bread provided an equal number of calories. Blood glucose and insulin were measured every 30 minutes up to 120 minutes. There was a 7 day washout period before the women consumed the other snack.
In both groups, the blood glucoses and insulin levels after consuming pistachios were significantly lower than whole bread at every time point that blood was drawn. The blood glucose and insulin levels remained within a normal range after consuming the pistachios.
This study indicates that pistachios may be an appropriate snack for pregnant women with impaired glucose tolerance or gestational diabetes mellitus.

Hernandez LM, et al. The effects of consuming a pistachio snack versus a refined carbohydrate snack on blood lipids, blood glucose, body weight, and body composition in young healthy adults. FASEB J. 2012;26:1b396.

The goal of this study was to determine if pistachio nut snack consumption would favorably affect plasma lipid profiles, food intake, body weight, and body composition in a non-obese, normolipidemic population compared to a refined carbohydrate snack.
41 healthy men and women were snacking on either pistachios or pretzels twice daily for three weeks.
Body weight and percent body fat were significantly decreased in the pistachio snack group. No significant differences were detected within or between groups for plasma total cholesterol, LDL-c, HDL-c, triglycerides or blood glucose (P>.05), but a trend towards a significant increase in serum triglycerides in the pretzel snack group (P=.056) was detected.
These results suggest that short-term consumption of a pistachio nut snack can decrease body weight and percent body fat as compared to a refined carbohydrate snack in young, healthy adults.

Hernandez-Alonso P, et al. Beneficial Effect of Pistachio Consumption on Glucose Metabolism, Insulin Resistance, Inflammation, and Related Metabolic Risk Markers: a Randomized Clinical Trial. Diabetes Care. 2014;10.2337/dc14-1431.

The goal of this study was to examine whether a pistachio-rich diet reduces the pre-diabetes stage and improves its metabolic risk profile.
54 people with pre-diabetes followed two diets, each for 4 months: a pistachio-supplemented diet and a control diet. A 2-week washout period separated study periods. Diets were isocaloric and matched for protein, fiber, and saturated fatty acids.
Fasting glucose, insulin, and markers of insulin resistance decreased significantly after the pistachio diet compared with the control diet.
Researchers conclude that chronic pistachio consumption is emerging as a useful nutritional strategy for the pre-diabetic state. Data suggest that pistachios have a glucose- and insulin-lowering effect, promote a healthier metabolic profile, and reverse certain metabolic deleterious consequences of pre-diabetes.

Hernandez-Alonso P, et al. Effect of pistachio consumption on the modulation of urinary gut microbiota-related metabolites in prediabetic subjects. Journal of Nutritional Biochemistry 45 (2017) 48-53

Changes in the composition of intestinal micro-organisms (microbiota) may impact metabolic and heart disease as well as longevity. This cross-over study investigated whether daily intake of pistachios could change urinary metabolites associated with the activity of gut microbiota in prediabetic subjects.
Investigators found that indeed pistachio consumption can modify the urinary profile of these metabolites. The changes were in the expected direction according to a beneficial effect of pistachio consumption on insulin resistance and Type 2 diabetes.

Holligan S, et al. A moderate-fat diet with pistachios lowers small-dense LDL and improves markers of insulin sensitivity in subjects with moderately-elevated cholesterol levels. FASEB J. 2013:27; A5071, 1057.3.

This research evaluated the dose-response effects of pistachios over four weeks, on markers of insulin sensitivity in 28 individuals with moderately elevated LDL-C.
Three test diets (SFA ≈ 8%; cholesterol • There was a significant diet effect on small-dense LDL levels and TG/HDL-C ratio.)
Researchers concluded that pistachio inclusion in a moderate-fat diet (≈ 35%) favorably affects insulin sensitivity and contributes to a beneficial cardio-metabolic profile.

Jenkins DJA, et al. Nuts as a replacement for carbohydrates in the diabetic diet. Diabetes Care. 2011;34:1-6.

One-hundred-seventeen men and women with type 2 diabetes ate either 475 calories, or 2 ounces, per day (as part of a 2,000 calorie diet) of either mixed nuts (which included pistachios), muffins, or half portions of each.
After three months, the group eating 2 ounces of nuts saw improvement in their blood levels of hemoglobin A1C, a measure of blood glucose over time, as well as a reduction in LDL ('bad') cholesterol.
The authors suggest that unsalted nuts, such as pistachios, as part of a calorie-controlled diet can improve diabetic control without weight gain.

Kendall CW, et al. Health benefits of nuts in prevention and management of diabetes. Asia Pac J Clin Nutr. 2010; 19(1):110-6.

This study reviews the scientific information on nuts, including pistachios, in the prevention and management of diabetes.
Nuts are low in carbohydrate, have healthy fats, and contain vegetable protein, fiber and magnesium. When eaten alone or with other foods, nuts tend to prevent a rapid rise in blood glucose levels.
The authors conclude that nuts can be included in diets to help manage diabetes.

Kendall CW, et al. Nuts, metabolic syndrome and diabetes 2010. Br J Nutr. Aug;104(4):465-73.

Metabolic syndrome is a combination of medical problems that increases the risk for heart disease and diabetes, and it can occur especially as people get older. It includes overweight, high blood pressure, high blood cholesterol and high blood glucose.
This study reviews the science of how nuts, including pistachios, may protect against metabolic syndrome.
The authors conclude that eating moderate amounts of nuts may be of benefit for healthy individuals, as well as those at risk for metabolic syndrome.

Sauder K, et al. Effect of pistachios on lipids, lipoproteins, glucose metabolism, and insulin sensitivity in type 2 diabetes. FASEB J. 2013;27:A2313,368.4.

This study compared the effect of two diets on lipids, lipoproteins, glucose metabolism, and insulin sensitivity.
28 adults with type 2 diabetes participated in a randomized, crossover, controlled-feeding study with four week diet periods. After a two week run-in on a typical Western diet, participants first consumed a low fat control diet, and then an isocaloric moderate fat pistachio diet, in which pistachios contributed 20% of energy. At the end of each diet period, researchers assessed lipid and glycemic parameters during a fasted state, and also during a standard 75g oral glucose tolerance test.
Compared to baseline, the control diet increased fasting triglycerides and the total:HDL cholesterol ratio, but these parameters were unaffected by the pistachio diet. Glucose and insulin levels were not affected by the diets; however, glycated hemoglobin was reduced from baseline following both diets, with significantly larger reductions following the pistachio diet than the control diet.
Taken together with other recent studies, these results suggest that pistachio consumption can benefit insulin sensitivity in adults with type 2 diabetes.

Sauder K, et al. Pistachio Nut Consumption Modifies Systemic Hemodynamics, Increases Heart Rate Variability, and Reduces Ambulatory Blood Pressure in Well-Controlled Type 2 Diabetes: a Randomized Trial. J Am Heart Assoc. 2014;3:e000873.

This study assessed the effect of pistachio consumption on blood pressure, systemic hemodynamics, and heart rate variability in adults with well-controlled type 2 diabetes.
30 adults (40 to 74 years) with type 2 diabetes participated in a randomized, crossover, controlled feeding study. After a 2-week run-in period, participants consumed a low-fat control diet (27% fat) containing low-fat/high-carbohydrate snacks and a moderate-fat diet (33% fat) containing pistachios (20% of total energy) for 4 weeks each, separated by a 2-week washout.
The pistachio diet significantly reduced total peripheral resistance, increased cardiac output, and improved some measures of heart rate variability (all P • A moderate-fat diet containing pistachios modestly improves some cardiovascular risk factors in adults with well-controlled type 2 diabetes.