New study says people with type 2 diabetes may not need to avoid potatoes completely

Type 2 diabetes, like most chronic diseases, is not easy to live with or manage. Apart from an unhealthy diet, inactivity and a genetic predisposition, some studies indicate that prolonged loneliness can also cause diabetes. Managing diabetes inevitably involves dealing with these risk factors, and maintaining a healthy diet is key.

The primary recommendation doctors give to those with type 2 diabetes is to maintain strict meal timings and consume a healthy diet. Usually, this means eating foods with a low glycemic index (GI), especially in the evenings, so that the postprandial or post-meal blood sugar levels of the patient do not shoot up. This is the reason why heavy meals or meals consisting of white rice, potatoes or sweets are things diabetes patients are asked to avoid.

But a new study published in Clinical Nutrition suggests that GI is not the only factor that needs to be taken into account when it comes to diabetes patients and that avoiding potatoes isn’t compulsory for them either.

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Why GI may not be the only viable parameter

The study starts out by mentioning the fact that the GI of carbohydrates forms the basis of dietary management of type 2 diabetes and the guidelines recommend the substitution of high GI carbs with low GI ones like wholegrain bread, legumes and low-GI basmati rice. The way the GI of all foods is calculated requires a person without blood sugar issues to consume each type of carb individually, typically after overnight fasting, and then the resulting spike in blood glucose is measured.

The researchers behind this study say that this method has major limitations. During actual meals, these carbs are rarely consumed in isolation and are more likely to be combined with other foods. In this case, the glycemic response (GR) to foods like potato will depend on the co-ingestion or other foods, their micronutrient content, the method of preparation and cooking - all of which can substantially affect the content of resistant starch. Repeated cooling and reheating carbs also affects the resistant starch content of potatoes, and can thereby influence the GR. Finally, GR will also depend on the individual’s variability instead of depending on just the GI of particular foods.

To eat or not to eat potatoes?

The researchers behind this study examined the impact of different methods of cooking potato when consumed as part of a mid-evening meal on postprandial glycemic response. The researchers additionally determined the nocturnal GR and postprandial insulin response in type 2 diabetes patients. They compared several potato-based meals with low-GI basmati rice to examine which has a worse postprandial and nocturnal GR.

The study included 24 men and women aged 58 years and older with type 2 diabetes. The participants were given a standardized breakfast and lunch. Dinner was provided at 6 pm and included boiled potatoes, roast potatoes and boiled potatoes cooled for 24 hours or low-GI basmati rice. Each meal contained 50 percent carbs, 30 percent fat and 20 percent protein. Blood samples from the participants were collected prior to and immediately after meals. They were also taken at 30-minute intervals for the following 120 minutes and a glucose monitor was worn to assess nocturnal GR.

The researchers found that none of the potato meals led to a negative postprandial GR, even though the consumption of the pre-cooked and reheated potato led to a slight spike. What’s more, the nocturnal GR after consuming potato-based meals was significantly lower than the levels of those who consumed low-GI basmati rice.

Based on these findings, it’s clear that avoiding potatoes is not a necessity for those who have type 2 diabetes. While it is recommended that freshly cooked, boiled or roasted potatoes are best-suited to those with diabetes, eating stale potatoes that have to be reheated should be avoided.

For more information, read our article on Diet for diabetes.

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