Diet is a complex and emotional topic, and can be hard to discuss objectively. But for those of us that live with diabetes, it is essential that we understand how different ways of eating impact our management.
There are several ways to judge a diet: weight loss, long-term adherence, and, specifically, measured health outcomes. We say the best “diet” is the one the you stick to, because most diets perform similarly for weight loss and adherence (and most have a lot in common -- no diet emphasizes processed foods, which we all agree are to be avoided).
Weight loss inherently increases insulin sensitivity (adipose tissue is an endocrine organ, and obese adipose tissue promotes an insulin resistance)!
Ways of eating that require less insulin (like low carb ones) also improve insulin sensitivity to some extent, both from weight loss and because less insulin means less hyperinsulinemia and resulting dysregulations.
So it can be really hard to judge diets as people with diabetes, since low insulin in general leads to more blood sugar stability; it’s easy to think that we should achieve that stability through whatever means necessary.
Way of Eating: It's More Than Just Blood Sugar
But diabetes is not just a disease of blood sugar, and the impact a diet has on our health is not always best represented by how in-range our blood sugars are. Insulin resistance, not just hyperglycemia, is a huge factor in diabetes complications, from neuropathy to heart attacks.
So in thinking about diets for overall health outcomes, we know that some dietary components increase insulin sensitivity (i.e. fiber and complex carbohydrates [vegetables] - increased fiber is associated with lower all-cause mortality for diabetics), while others decrease insulin sensitivity (i.e. most dietary fat - a high fat high protein meal requires 65% more insulin than LFLP of equal carbs).
This is also supported by epidemiological data! In general, the places around the world with the best health outcomes eat whole (unprocessed) food diets rich in plant-based carbs (this means, vegetables), plus fiber, and lower in sources of animal fat and protein. These mediterranean-style diets are associated not just with more and longer in-range blood sugars, but better health overall.
Show Me the Data
A study in 2019 showed, in great detail, just how important these plant-based ways of eating (again: making vegetables your primary source of food) are for people with diabetes. And in particular, type 2 diabetes.
This study examined the relationship between plant-based dietary patterns and the risk of type 2 diabetes. Not surprisingly, the researchers found that diets rich in plant foods, and low or absent in animal foods, were linked to significantly lower rates of type 2 diabetes.
This systematic review and meta-analysis included >300,000 people from 9 major prospective studies on plant-based eating patterns (including vegetarian and vegan) who also had type 2 diabetes.
All studies adjusted for body mass index (a key risk factor for type 2 diabetes), as well as age. Most studies also adjusted for many other potential confounders, like physical activity, smoking, family history of diabetes, and total daily calorie intake.
All but 2 of the studies showed that plant-based diets were linked to a statistically significantly lower risk of type 2 diabetes; when all 9 study results were combined, the risk reduction was 23%. In the 4 studies that ranked plant-based diets according to healthy vs less-healthy foods (eg, refined grains & added sugars), the combined risk reduction for healthy plant-based diets was 30%.
The dose-response curves showed that the more plant-based the diet, the lower the risk of type 2 diabetes, in a linear fashion.
What Does It All Mean?
The authors note that plant-based diets (ways of eating that are high in vegetable consumption) may lower risk of type 2 diabetes by multiple mechanisms: higher fiber, antioxidants, unsaturated fats, and reduced inflammation, with less heme iron, saturated fats, and lower risk of weight gain.
It’s not all or none! Every small step you take incorporating more whole foods and more vegetables into your life will be met with better insulin sensitivity and better overall health outcomes.