Prescribing Fruits and Vegetables to Patients With Type 2 Diabetes: A Comprehensive Guide

Diabetes now affects roughly 11% of the US population. Additionally, one-third of US adults meet the criteria to be diagnosed with prediabetes, which, when left untreated, leads to type 2 diabetes. By the year 2045, upwards of 700 million people worldwide could be impacted by this mostly preventable chronic disease. Type 2 diabetes significantly reduces quality of life and increases the risk of other serious chronic diseases like dementia, heart disease, and kidney failure.

Since type 2 diabetes is largely a disease of lifestyle, nutrition can be used as a therapeutic tool to help prevent, manage, and even reverse it. Confusion exists when it comes to fruits and vegetables in a diabetes meal plan. This article will discuss why fruits and vegetables should be recommended for people at risk of and with type 2 diabetes, along with additional dietary considerations for diabetes.  

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Understanding Type 2 Diabetes

Glucose is a main fuel source for the cells of the body, and it mostly comes from the digestion of foods that contain carbohydrates. When carbohydrate-containing foods (starchy foods, fruit, and dairy products) are eaten, the pancreas produces the hormone insulin. Insulin serves to allow glucose to enter our cells to be used for energy. For people who develop type 2 diabetes, the cells of the body no longer recognize insulin, or the pancreas can’t produce enough insulin to keep up with the demand.  The end result is a high level of glucose in the bloodstream, which can be toxic to the tissues and organs of the body.

Common symptoms of type 2 diabetes include:

• Blurred vision
• Cold sweats
• Difficulty with wound healing
• Dizziness
• Excessive thirst and urination
• Extreme hunger
• Fainting
• Fatigue
• Frequent infections
• Patches of dark skin, especially on the back of the neck
• Unexplained weight loss

Type 2 diabetes develops as a result of the interplay between genetics and lifestyle. While type 2 diabetes was once thought of as a disease of adulthood, we’re now seeing it in children, mostly as a result of the obesity epidemic. Obesity, especially excess amounts of abdominal fat from poor diet, lack of physical activity, unmanaged stress, and disrupted sleep, leads to insulin resistance and increases the likelihood of type 2 diabetes. Other risk factors include:

• Having a family history of diabetes
• Being African American, American Indian, Asian American, Hispanic/Latino, or Pacific Islander
• Being sedentary
• Having prediabetes
• Having a history of gestational diabetes (diabetes during pregnancy)

If blood sugar control is poor, patients with type 2 diabetes can develop cardiovascular disease, kidney failure, liver disease, numbness in the limbs (neuropathy), and blindness. Fortunately, there are many lifestyle  therapies, like diet, that are very effective for managing the underlying causes of type 2 diabetes. 

Diabetes Management with Diet

Inflammation, insulin resistance, and obesity are common underlying features of type 2 diabetes. Poor diet is a leading factor in the development of all of these, so nutrition-related changes should be a top priority when it comes to type 2 diabetes treatment.

Research has found inflammatory diets that contain ultra-processed foods, excess added sugar and alcohol, refined grains, and inflammatory fats to increase the likelihood of insulin resistance and type 2 diabetes. In addition, a lack of adequate nutrients like zinc, chromium, magnesium, and vitamin D can also increase risk.

Dietary patterns that are anti-inflammatory and low-glycemic (like the Mediterranean and DASH diets) have been found to delay and even prevent type 2 diabetes development. But nutrition is also a powerful tool for normalizing blood sugar levels, improving quality of life, and reducing the likelihood of diabetes-related complications in those who already have type 2 diabetes.  

There’s no one-size-fits-all diet for type 2 diabetes; rather, the nutrition plan needs to be personalized to the patient based on their lifestyle and motivation to change, but socioeconomic and cultural factors also need to be taken into consideration.

Prescribing Fruits for Diabetes

Increased intake of fruit has been found to be protective against type 2 diabetes. This benefit may be due in part to the fiber and polyphenol content, which help to preserve insulin sensitivity and reduce oxidative stress. Fruit also contains a variety of vitamins and minerals important for proper insulin regulation. A high intake of fruit may modulate the gut microbiome in such a way as to prevent type 2 diabetes. 

While patients with type 2 diabetes are often educated to avoid fruit, a meta-analysis found no negative impact on fasting glucose, insulin levels, or hemoglobin A1c (HgbA1c). Patients with type 2 diabetes who consume fruit may actually have better glycemic control.

The glycemic index (GI) is a scale that ranks how certain carbohydrates impact blood sugar.  Low glycemic foods may have a reduced impact on glucose levels after eating, whereas high glycemic foods may lead to significant increases in blood sugar after consumption. However, this ranking system doesn’t take into consideration individual variation, what the food item is being consumed with (i.e., protein and fat), and the method of cooking. 

Most patients with type 2 diabetes can likely enjoy a serving of whole fruit (a small to medium piece of fresh fruit or 1 cup of diced fruit) with meals without seeking out low GI options specifically. Berries, with their high polyphenol content, may be particularly beneficial when it comes to blood sugar control. Types of fruit to avoid when you have type 2 diabetes include canned fruit in heavy syrup, frozen fruit with added sugar, and fruit juice.

Vegetables for Diabetes Control

As a group, vegetables contain fiber, vitamins, minerals, and polyphenols, all of which play a role in insulin sensitivity and glycemic control. There are two main categories of vegetables—starchy and non-starchy. Starchy vegetables, like potatoes, peas, and corn, have more carbohydrates, so they may lead to higher blood sugar levels after a meal when compared to non-starchy vegetables like leafy greens and beets. 

While there are no vegetable varieties that need to be strictly avoided by people with type 2 diabetes, prioritizing green leafy and yellow vegetables due to their polyphenol content and cruciferous vegetables (like broccoli, cabbage, Brussels sprouts, and kale) for their glucosinolates may provide important blood sugar benefits. Many nutrition plans recommend filling half of the plate with non-starchy vegetables and limiting starchy varieties to 1 serving per day.

Creating a Balanced Diabetes Diet Plan

While meeting fruit and vegetable targets is desirable, the diet in its entirety is the priority. People with type 2 diabetes will benefit most from a well-balanced meal plan of whole-unprocessed foods that includes adequate amounts of lean protein, healthy fat, and wholesome carbohydrates. Additionally, adding vinegar to high glycemic meals may improve the glycemic response after meals in those with type 2 diabetes..

Lean Protein

Protein helps to control blood sugar levels and promotes satiety. For type 2 diabetes patients with healthy kidney function, increasing protein intake to 20 - 30% of total daily calories may be beneficial. If kidney function is poor, then lower protein intake may be warranted. Lean sources of animal protein like chicken, fish, turkey, lean red meat, and eggs can be enjoyed with each meal. Vegetarian sources of protein like soy foods, legumes, nuts, and seeds contribute both protein and carbohydrate to meals.   

Healthy Fat

Healthy fats help to promote satiety, provide structure to cells, support brain function, and help with the absorption of fat-soluble vitamins. Healthy fats, like monounsaturated fats (olive oil and avocado oil) and omega-3 fats (fatty fish), have been found to decrease inflammation and improve lipid levels. There’s no formal recommendation on the amount of fat to consume for people with type 2 diabetes, so personalization is key. It’s advisable to reduce the amount of saturated and trans fats in the diet to prevent cardiovascular complications. Partially hydrogenated or hydrogenated fats should be strictly avoided.

Wholesome Carbohydrates

The total amount of carbohydrates in the diet significantly impacts blood glucose control, but patients with type 2 diabetes don’t need to avoid all carbohydrates. A lower carbohydrate diet, consisting of 40-45% carbohydrate, has been shown to improve blood sugar control and also reduce the need for diabetes medication. 

Nutrient-dense carbohydrates that contain a good amount of fiber should be emphasized. Legumes like beans, lentils, and soybeans, and whole grains like quinoa, millet, and oats are high in fiber, which can help to lower blood sugar and lipid levels and reduce gut inflammation. These wholesome carbohydrates also contain valuable micronutrients like magnesium and potassium that are often missing in the standard American diet. 

Vinegar

Acidity can slow gastric emptying, which may help to improve blood sugar levels after meals. Studies have found the addition of vinegar (which contains acetic acid) to high GI foods can reduce the glycemic response in those with type 2 diabetes. While it’s unclear how much vinegar is necessary, studies have found 15-20 milliliters to improve the glycemic response and insulin sensitivity. Type 2 diabetes patients may wish to add a vinaigrette dressing made with olive oil and vinegar when appropriate. 

How Can Functional Medicine Labs Assess Diabetes and Nutritional Status?

Conventional labs for type 2 diabetes typically include fasting glucose and an HgbA1c level. While these values can be helpful, they don’t provide a complete picture of overall glycemic control or how well the treatment plan is working. Several functional medicine labs can be used to determine how well type 2 diabetes is controlled and if there are underlying factors that can be addressed to further improve patient outcomes. In addition, continuous glucose monitoring now provides real time feedback for patients with type 2 diabetes.  

Blood Sugar Monitoring

Measuring biomarkers associated with the diagnosis of diabetes, like fasting insulin, fasting glucose, and hemoglobin A1c can be used to give a more complete picture of blood sugar regulation.

Comprehensive Stool Analysis

Poor gut health may be an underlying factor in obesity and type 2 diabetes. The GI-MAP Stool Test from Diagnostic Solutions measures gastrointestinal microbial DNA to detect microbial imbalances, microbes that may contribute to illness, and indicators of digestion, absorption, inflammation, and immune system function. Practitioners can use test results to personalize a plan to improve microbial balance and GI function, which may help to improve insulin resistance and blood glucose levels. 

Micronutrient Testing

Since nutrient deficiency and insufficiency may contribute to high blood sugar, obesity, and insulin resistance, it’s important to determine nutrient status. The SpectraCell Micronutrient test helps to determine the levels of certain vitamins, minerals, and other nutrients in the blood, but it also provides insight into their performance in the body. If nutrient insufficiency or deficiency is uncovered, practitioners can tailor the meal plan or use targeted supplementation to improve levels. 

Continuous Glucose Monitoring

A continuous glucose monitor (CGM) is a wearable device that patients with prediabetes and type 2 diabetes can use to track their blood sugar levels over a 24 hour period. Instead of fingersticks, this device uses a small filament inserted into the arm or abdomen to provide a constant flow of information about glucose levels. CGMs can help patients and practitioners learn about the individual response to foods (and lifestyle) in order to personalize the treatment plan. 

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Educating Diabetes Patients on Diet

In addition to a nutrient-dense meal plan, patients with type 2 diabetes will want to consider a number of other important factors.

Meal Timing and Portion Sizes

Patients with type 2 diabetes should create a routine eating schedule and avoid skipping meals (especially if on insulin) to prevent hypoglycemia. Routine meals, spaced 4-5 hours apart, also allow for complete digestion and the intake of adequate nutrients, which are both important for satiety and blood sugar control. Likewise, portion control can help to promote healthy weight loss and appropriate postprandial glucose levels.

Nonnutritive Sweeteners

Many products marketed to people with type 2 diabetes contain artificial sweeteners. While some research indicates no harmful impact, newer studies have found a variety of nonnutritive sweeteners to negatively impact the gut microbiome and disrupt blood sugar regulation. Patients should be educated to limit nonnutritive sweeteners and instead opt for small amounts of natural sweeteners like honey or dates.

Alcohol Intake

Alcohol intake should be limited for people with type 2 diabetes since it can increase the likelihood of hypoglycemia, especially for those on insulin. But alcohol may also lead to unwanted weight gain or make losing weight difficult. If patients choose to consume alcohol, it should be done with a meal instead of in isolation. 

Exercise

Consistent exercise can help people with type 2 diabetes control their blood sugar levels, reach and maintain a healthy weight, and reduce the risk of diabetes complications. Patients should be educated on the importance of a well-balanced exercise plan that includes a combination of cardio, resistance, and flexibility training. If patients are new to exercise, simply taking a 30-minute walk after meals may help to significantly improve the blood glucose response. For patients who are able to exercise more intensely, incorporating high intensity interval training (HIIT- a short burst of activity like sprinting followed by a recovery session or equal or longer duration and then repeat several times) may provide even more benefits when it comes to blood sugar control.

It’s important to check blood sugar levels before exercise. If glucose is less than 70 mg/dL, the exercise session should be delayed. If blood sugar is less than 100 mg/dL before exercise, patients may need a snack consisting of 15-30 grams of carbohydrate. If exercise intensity is moderate, 15 grams of carbohydrates (like one small piece of fresh fruit or 8 ounces of milk) may need to be consumed for every 30-60 minutes of exercise.

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Summary

Type 2 diabetes and prediabetes impact a significant portion of the population. Without effective treatment, those with prediabetes will likely develop type 2 diabetes, and those already diagnosed with the disease can develop serious complications like heart, liver, and kidney disease. 

Type 2 diabetes development is closely related to diet. An inflammatory diet high in ultra-processed foods, added sugar, and unhealthy fats can increase the risk of insulin resistance and obesity, both factors tied to type 2 diabetes development. On the other hand, anti-inflammatory diets that contain adequate amounts of fiber, vitamins, minerals, and phytonutrients can protect against type 2 diabetes development and also help to better manage blood sugar levels in those with the disease. 

While there’s no one perfect meal plan for patients with type 2 diabetes, following a diet that includes adequate amounts of fruits and vegetables can help improve blood sugar levels. Fruits and vegetables contain a wide variety of vitamins, minerals, fiber, and polyphenols, which help support insulin sensitivity and promote glycemic control. In addition to fruits and vegetables, a diabetes meal plan should also contain adequate amounts of lean protein, healthy fats, and wholesome carbohydrates.