Research on Type 2 Diabetes/ Prediabetes

Below you will find a growing collection of dietary and health research on type 2 diabetes treatment, with a particular focus on low carbohydrate diets.

Overview

It has long been believed that when people get diagnosed with type 2 diabetes, they’re destined to get progressively worse, take more meds and suffer bad health. That’s simply not the case!

While type 2 diabetes is not reversible from a diagnostic standpoint (once a person has it, they have it), diabetes can be reversible from a physiological standpoint, in many. That is, a person can achieve normal blood sugar levels and metabolic function, and frequently reduce their need for medication. They can live and function like a non-diabetic person.

In addition, people may be able to put their diabetes in remission – defined as HbA1c <6.5% for at least 3 months without glucose-lowering medication.

Research shows this is true (see below) and in our experience with members and subscribers, people are achieving this everyday, even if they’ve had type 2 diabetes for 20 years!

IMPORTANT NOTE: The majority of the research that follows is around type 2 diabetes treatment. It’s important to differentiate ‘reduction of diabetes risk’ from ‘diabetes treatment.’ These are often lumped into the same category but they are two very different concepts. Here at DMP our main focus is on diabetes treatment, along with prediabetes diet and digital lifestyle interventions that get results.

Blood Sugar & A1c

BLOOD SUGAR: Blood sugar is a measure of glucose/ sugar in the blood at any one time. Throughout the day blood sugar can fluctuate in response to numerous factors, mainly food but also exercise, stress, sleep, medications and so forth.

The body is designed to maintain blood sugar levels in a healthy range. It is well established that people with type 2 diabetes and prediabetes should work toward the goal of having normal blood sugar levels because high blood glucose levels causes damage to cells and vessels throughout the body, which can lead to health complications.

Normal blood sugar levels are 70-100 mg/dL or 4-5.6 mmol/L (fasting) and 140 mg/dL or 7.8 mmol/L 2-hours after meals.

While diabetes organizations such as American Diabetes Associations may recommend a higher range (180 mg/dL), research (1,2) shows glycemic values in the normal range are associated with the least risk of complications, if patients can achieve these levels over time.  

A1C: A1C is a blood test that provides an average blood sugar measurement for the past 2-3 months. It’s a more accurate measure than blood sugar because it can’t be influenced by meals a person has had today or the day before. A1c is provided as a percentage and the normal range is 4-6%. In some diabetic patients, a higher level of 7-8% may be more realistic. The goal is, where possible, encourage a person to work toward a normal healthy range.

Research has indicated (1,2) that for many people with type 2 diabetes, clinical recommendations for HbA1c levels should be less than 6.5%. HbA1c values in the normal range (less than 6%) are associated with the least risk of complications, if patients can realistically achieve these levels over time.

KEY POINT: Encourage people to achieve glycemic levels in the normal range, if possible, as this shows decreased risk of complications.

Nutrition Therapy and Glycemic Control

Research shows:

• Nutrition therapy has similar or greater effectiveness than medications (3)
• Nutrition therapy can help people with type 2 diabetes reduce A1c levels by up to 2% (3,4).
• Lifestyle intervention provides a 58% risk reduction for diabetes diagnosis in people with prediabetes (4,5).
• While a variety of eating patterns can help treat or prevent, low carb diets are among the most studied eating patterns for type 2 diabetes (3,6).

Type 2 Diabetes Dietary Recommendations

While it is true that there is no one-size-fits-all diet, the ADA Standards of Medical Care in Diabetes: 2022 recommends that to improve health in type 2 diabetes, use strategies common among healthy eating patterns:

“1) emphasise non-starchy vegetables; 2) minimise added sugars and refined grains; and 3) choose whole foods over highly processed foods to the extent possible (p.S50).” 

Here at DMP, we have been educating people about nutrient-dense whole food intake since 2015, with emphasis on:

• A high intake of non starchy vegetables
• The inclusion of unprocessed protein sources
• Choosing monounsaturated fat as the predominant dietary fat, but not avoiding nutrient-dense foods that contain polyunsaturated or saturated fats
• A moderate intake of lower carb fruits
• Regular intake of nuts and seeds
• Inclusion of low-fat or full fat dairy products and other whole foods

In addition, a large amount of evidence continues to demonstrates that a lower carb diet is the best dietary pattern for diabetes treatment.

Prior to late 2018, diabetes organizations were very slow to accept low carb diets, however, ADA has for the first time acknowledged it in their 2019 nutrition therapy recommendations that:

• “Low carb eating patterns are among the most studied eating patterns for type 2 diabetes.” 
• “Reducing overall carbohydrate intake for individuals with diabetes has demonstrated the most evidence for improving glycemia.”
• “For select adults with type 2 diabetes not meeting glycemic targets or where reducing antiglycemic medications is a priority, reducing overall carbohydrate intake with low- or very low-carbohydrate eating plans is a viable approach.”

Likewise, Diabetes Australia released a position statement in August 2018 acknowledging acceptance of a low carb diet as an effective treatment strategy for people with type 2 diabetes.

Now, in the 2022 guidlines, the ADA continues to note that:

“Reducing overall carbohydrate intake for individuals with diabetes has demonstrated the most evidence for improving glycemia (p.S63).”

As you will soon see in the research outlined below, the reason for their change of heart is because low carb diets have continuously shown better outcomes for people with type 2 diabetes:

• Decreased blood glucose
• Lower A1C
• Decreased cholesterol
• Increased HDL
• Increased weight loss
• Lower medication need

Our nutrition education has always and continues to focus on a low carbohydrate whole food eating plan that aligns and stays up to date with current scientific research about the most effective diets to treat type 2 diabetes.

Research Links

Low Carb Diet and Type 2 Diabetes Research

In 2015, Feinman RD, et al., established a definition of carbohydrates in the diet:

• Very low carb ketogenic diet: 20-50 g per day. Below 10% intake of 2000 calorie diet.
• Low carbohydrate diet: Below 130 g per day. Below 26% total energy intake. 
• Moderate carbohydrate diet: 26-45% total energy intake 
• High carbohydrate diet (low fat): Above 45% total energy intake 

In recent years, there has been an abundance of evidence (see full reference list below) indicating low carb diets lead to greater reductions in A1c levels compared to higher carb diets.

The chart below by Wheatley et al. 2021 shows the outcomes of low carb diets in comparison to other diets.

All the items marked LCD have improved on a low carb diet in people with type 2 diabetes – note body weight in the first column.

The grey boxes indicate where the items were not reported in studies. The dash (-) indicates no differences between diet groups. 

This is a really great chart to visually show that compared to other diets, a low carbohydrate eating plan improves:

• Body weight
• HbA1c
• Triglycerides
• HDL cholesterol

In the long term (2+ years) other diets have also faired well in terms of A1c reduction. However, consistently low carb diet studies report a reduced need for medication and reduction in glycemic variability, which indicates better overall metabolic function and glycemic control. 

CLICK HERE to view a table summarizing research on low carb vs low fat and higher carbohydrate diets.

You can also find links below to various studies about dietary carbohydrates.

Research Links

Weight Loss & A1C Diets Comparison

Source: Sandouk Z, et al. Diabetes with obesity: Is there an ideal diet? Cleveland Clinic Journal of Medicine. 2017;84(1):S4-14.

Carbohydrates

The main nutrient that influences blood glucose and insulin is carbohydrates. It is well acknowledged that while the type of carbohydrate is important the amount has the greatest impact upon blood sugar and insulin response.

Since this is the case, monitoring carbs/ carb counting remains a key strategy for people to achieve good control. The ADA has only recently (2019) acknowledged that “reducing overall carbohydrate intake for individuals with diabetes has demonstrated the most evidence for improving glycemia.”

ADA acknowledge that “studies examining the ideal amount of carbohydrate intake for people with diabetes are inconclusive.”

While that is true, evidence continues to demonstrate that a low carbohydrate approach is an effective way to control diabetes, consistently producing the following results:

• A1c reduction
• Immediate reduction in fasting glucose levels
• Lower medication usage
• Lower risk of hypoglycemia
• Improved cholesterol profile
• Decreased triglycerides and increased HDL

The ADA, Diabetes Australia and Diabetes UK now acknowledge that a low carb dietary pattern can help with diabetes management, a big change since we founded DMP in 2015 when they were all against this dietary pattern.

How Many Carbohydrate Should People Eat?

In 2015, Feinman RD, et al., established a definition of carbohydrates in the diet:

• Very low carb ketogenic diet: 20-50 g per day. Below 10% intake of 2000 calorie diet.
• Low carbohydrate diet: Below 130 g per day. Below 26% total energy intake. 
• Moderate carbohydrate diet: 26-45% total energy intake 
• High carbohydrate diet (low fat): Above 45% total energy intake 

A low carbohydrate diet is considered anything below 130 grams per day, or below 26% of total calories. A low carb diet is not to be confused with a ketogenic diet, which is below 10% of caloric intake. DMP is not a ketogenic website. Both low and very low ketogenic diets improve outcomes in people with type 2 diabetes.

Still, even modest decreases in carbs (20-40% of total calories) can provide benefits for people with type 2 diabetes and prediabetes. The point is, carbohydrate reduction should be encouraged in people with type 2 diabetes.

Low Carb/ Fat/ Protein Ratios

There is no ideal carb, fat, and protein ratio. But let’s calculate two varying amounts of low carbohydrate diets. 

In a 1600 calorie diet, the carb/protein/fat ratio of an ideal low carb diet breaks down as follows:

• 10-20% Carbs: 40-80 g/ d
• 20-30% Protein: 80-120 g/d
• 40-60% Fat: 70-110 g/d

Or at a slightly higher carb intake:

• 25% Carbs: 100 g/ d
• 20-30% Protein: 80-120 g/d
• 40-50% Fat: 70-89 g/d

Research Links

Fat & Cholesterol

Over the years we’ve all been led to believe that eating fat is bad, so we’ve been pushed toward eating low fat diets. But unfortunately, low fat diets are higher in carbs and sugar, which is not ideal for people with type 2 diabetes/prediabetes.

According to the ADA, “Data on the ideal total dietary fat content for people with diabetes are inconclusive. The type of fats consumed is more important than total amount of fat when looking at metabolic goals and CVD risk. An eating plan emphasizing elements of a Mediterranean-style diet rich in monounsaturated fats may improve glucose metabolism and lower CVD risk and can be an effective alternative to a diet low in total fat but relatively high in carbohydrates.”

While it is agreed that monounsaturated fats provide cardiovascular benefits. As emerging evidence continues to appear, we are learning more about the important role of fat and cholesterol, along with the need to change our perspectives on their intake, including saturated fat intake.

Fat

READ: The definitive guide to fat and diabetes

Research Links

Cholesterol

Investigations into the role of cholesterol have gained more attention in recent years.

In 2015, the Dietary Guidelines Assessment Committee (DGAC) released preliminary updates on revisions that were recommended to the American Dietary Guidelines.

Their preliminary statement about cholesterol:

“Cholesterol. Previously, the Dietary Guidelines for Americans recommended that cholesterol intake be limited to no more than 300 mg/day. The 2015 DGAC will not bring forward this recommendation, because available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol… Cholesterol is not a nutrient of concern for overconsumption.”

The Academy of Dietetics and Nutrition “supports the DGAC in its decision to drop dietary cholesterol from the nutrients of concern list and recommends it deemphasize saturated fat from nutrients of concern, given the lack of evidence connecting it with cardiovascular disease.”

And as for fat…”The Academy suggests that HHS and USDA support a similar revision deemphasizing saturated fat as a nutrient of concern. It appears that the evidence summarized by the DGAC suggests that the most effective recommendation for the reduction in cardiovascular disease would be a reduction in carbohydrate intake with replacement by polyunsaturated fat.”

Since then an emerging body of evidence continues to indicate that cholesterol in the diet is not a concern. In fact, carbohydrates are more closely associated with higher cholesterol than cholesterol-rich of natural-fat-filled foods. A 2018 study looking at cardiovascular risk factors for 158 countries found that the single biggest risk factor is consumption of carbohydrates. And surprisingly, it’s not just sugar, as we might expect. It’s foods such as cereals, wheat and starchy carbs – all of which are high in carb content.

However, we know that dyslipidemia is common in type 2 diabetes, so what can people expect from a low carb diet?

In most cases, when people switch to a low carb diet:

• Triglycerides go down.
• HDL cholesterol (the “good” stuff) goes up.
• Total cholesterol either goes down or stays the same .
• LDL cholesterol has a tendency to stay the same. However, the LDL particle size often increases (large, fluffy particles), and the LDL particle number goes down (more large particles equals less overall particles).

For those that continue to experience higher cholesterol levels on a low carb diet, there are strategies to manipulate the diet which can help. 

READ: Confusions about cholesterol and diabetes resolved

Research Links

Protein

Protein improves satiety and hunger signals and makes up part of a healthy balanced diet. People with type 2 diabetes and prediabetes should be encouraged to eat healthy protein from lean meats, poultry, game, eggs, nuts, seeds and dairy products.

According to the ADA, “research is inconclusive regarding the ideal amount of dietary protein to optimize either glycemic control or CVD risk. Some research has found successful management of type 2 diabetes with meal plans including slightly higher levels of protein (20–30%), which may contribute to increased satiety.”

There is evidence to suggest that even an intake making up 35% of diets in type 2 diabetes causes no harm.

Additionally, research shows protein may enhance the insulin response to carbohydrates. 

Research Links

We hope you find this research useful in your pursuit to help people with type 2 diabetes and prediabetes gain better outcomes.

If you know of further research that would contribute to our collection, or you have further queries, please contact us.