Eating Almonds Before Meals Improves Glucose Levels in Some People With Prediabetes

Two new research studies with almonds, one conducted over three days and the other over three months, demonstrated benefits to blood sugar control for Asian Indians with prediabetes and overweight/obesity – and the three-month almond intervention broke new ground, reversing prediabetes, or glucose intolerance, to normal blood sugar levels in nearly one quarter (23.3%) of the people studied.

In both studies, 60 people ate 20 g (0.7 oz) of almonds, around a small handful, 30 minutes before breakfast, lunch, and dinner throughout the study durations. Researchers expressed their enthusiasm for these almond studies and the first-of-its-kind statistically significant reduction in measures of prediabetes by calling the reversal of prediabetes through diet "the holy grail of medicine." Better glucose control over time through dietary strategies like including almonds could help stave off diabetes progression. Nearly 70% of individuals with prediabetes will develop diabetes within their lifetime. 

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Both studies were randomized controlled trials funded by the Almond Board of California. The researchers hypothesized that the almond snack before major meals, known as "preloading," would reduce glucose and insulin fluctuations after meals and reduce overall hyperglycemia compared to the control diet. The findings complement the breadth of research on different populations on how almonds support healthy blood sugar as part of a balanced diet.

"Results from our studies indicate almonds might be a key differentiator in helping regulate blood glucose levels as part of a dietary strategy. These results showcase that the simple addition of a small portion of almonds before each meal can quickly and drastically improve glycemic control in Asian Indians in India with prediabetes in just three days. Eating 20 g of almonds 30 minutes before an oral glucose load showed a significant decrease in blood sugar and hormones. Almonds' nutritional makeup of fiber, monounsaturated fats, zinc, and magnesium work together to help provide better glycemic control and reduce hunger," said lead author Dr. Anoop Misra, Professor and Chairman, Fortis-C-DOC Centre of Excellence for Diabetes, Metabolic Diseases, and Endocrinology (New Delhi).

"Our outcomes provide a promising dietary strategy for reducing prediabetes progression and returning people to normal glucose regulation." .

His collaborators agree. "In view of the increasing prevalence of diabetes, dietary strategies like consuming almonds 30 minutes before major meals offers a good option to decrease the spike in blood glucose levels after meals," said Dr. Seema Gulati, head, Nutrition Research Group, National Diabetes, Obesity, and Cholesterol Foundation.

The longer-term study:

This three-month longer-term study was with overweight or obese Asian Indian adults who had prediabetes. Participants were randomized into either the almond treatment group or into the control group, and both were provided with diet and exercise counseling as well as home-use glucometers to measure their glucose levels, which were recorded in diaries along with dietary intake and exercise.

Study measures comprised a variety of anthropometrics: body weight; circumferences of waists, hips, and arms; skinfolds of customary locations of the body; and body fat estimates. Biochemical measures included insulin, blood sugar, hemoglobin A1c, C-peptide, glucagon, proinsulin, high sensitivity C-reactive protein, tumor necrosis factor alpha, and lipids.

Eating 20 g (0.7 oz) almonds ahead of breakfast, lunch, and dinner, for three months resulted in first-of-its kind statistically significant reductions for the treatment group in body weight, body mass index, waist circumference, skinfold tests for shoulder and hip areas, as well as improved handgrip strength. Similarly, reductions were seen for fasting glucose, postprandial insulin, hemoglobin A1c, proinsulin, total cholesterol, LDL-cholesterol, and very low-density lipoprotein. Importantly, no changes occurred with beneficial HDL-cholesterol, meaning this cardioprotective lipid was maintained despite other observed biochemical alterations.

These substantial metabolic improvements led to nearly one-fourth (23.3%) of the prediabetes study participants returning to normal blood glucose regulation. These findings are meaningful for global public health given the prevalence of diabetes, the troubling rates of progression from prediabetes to diabetes, and are specifically relevant to Asian Indians in India who are disproportionately impacted because of their greater tendency to progress from prediabetes to diabetes.

Researchers think the nutrients in almonds may play a role in the observed health benefits from this study. "The natural combination of monounsaturated fatty acids and soluble fiber could be responsible for the positive metabolic outcomes," Dr. Misra said. "Almonds may slow stomach emptying, which could help people ingest less food and fewer calories to promote weight management, which is important in helping reverse the course of prediabetes back to normal blood sugar regulation."

While the results are extremely promising, the researchers noted some limitations, including the relatively small sample size and limited period of intervention. They also noted that the study included Asian Indians who had well-controlled prediabetes, and the researchers cannot extrapolate the same impact of a premeal load of almonds in participants with type 2 diabetes. Including participants with poorly controlled metabolic states as well as those with diabetes could be useful.

The short-term study: 

• Part 1: One Day Oral Glucose Tolerance Testing (OGTT): Participants were first divided into two groups of 30. The first group consumed a 20 g (0.7 oz) portion of almonds. The second group received no almonds and both groups were given an OGTT.
   
• Part 2: Three-Day Blood Glucose Monitoring: Using a continuous glucose monitoring system (CGMS), researchers compared the glycemic effects of preloading three meals a day (breakfast, lunch, dinner) with 20 g (0.7 oz) of almonds for three consecutive days in 60 participants, with the participants who received no preloading of almonds.

Upon conclusion of the short-term study, researchers found that indicators for hyperglycemia, such as blood glucose, serum insulin, glucagon, and C-peptide (only OGTT results) were lower for the almond group versus the control group. There was an 18.05% decrease in PPBG levels, indicating improved regulation of glycemic responses among the almond consumers.

Results from the continual glucose monitoring system showed statistically significant improvement in glucose variability over the first 24 hours in the almond group, indicating appropriate glucose control. Specifically, PPHG levels were lowered by 10.07% in the almond group compared to control. Additionally, treatment with premeal almond loading significantly improved several indicators that reflect daily glycemic control compared to the control group: lower mean 24-hour blood glucose concentration, less time spent above an elevated blood glucose level of 140 mg/dL, lower peak 24-hour glucose levels, decreased post-prandial blood glucose levels, lower minimum glucose levels at night, and lower overall hyperglycemia. 

Limitations of the short-term study include a limited period of intervention with a smaller sample size comprising people with prediabetes. Also, nutritional intervention studies can trigger behavioral changes in both groups as the participants are made aware of their risk during the recruitment process and were given dietary instruction prior to the study. Further research is needed to investigate the effects of almond preloading consumption on the same measures in different ethnicities and in individuals with diabetes and normal body weights to be able to provide broader recommendations.

In summary, with both studies, Dr. Misra and colleagues found that study participants who ate 20g (0.7oz) of almonds 30 minutes before a meal showed significant improvements in glycemic control compared to not eating almonds before meals over three months. Almonds can be part of a nutritious dietary solution offering good potential for the reversal of prediabetes to normal glucose regulation in some Asian Indians and therefore potentially prevent or delay the development of diabetes in people with prediabetes.

A one-ounce (28 g) serving of almonds provides 4 g (14% DV) fiber and 15 essential nutrients, including: 77 mg (20% DV) magnesium, 210 mg (4% DV) potassium, and 7.27 mg (50% DV) vitamin E, making them a perfect nutrient-rich snack for those with impaired glucose tolerance or type 2 diabetes.