Potatoes are one of the first food most people feel they need to stop eating once diagnosed with prediabetes or type 2 diabetes. Thankfully, there’s no need to eliminate potatoes; eaten in moderation and paired with healthy fats, protein and fibre, they can be part of a healthy, balanced diet that helps to control your blood sugar.

Now that’s cleared up, you may wonder what type of potatoes are best – sweet or white? The short answer is that sweet potatoes are better, but it depends on how you cook them and the type of white potatoes you compare with them.

Keep reading to learn more.

Nutritional Facts – Sweet Potatoes vs. White Potatoes

Sweet potatoes

Sweet potato (Ipomoea batatas) belongs to the Convolvulaceae family of flowering plants. Over 400 varieties of sweet potatoes exist, and their flesh can be white, yellow, orange or purple.¹ Sweet potatoes are classified into two categories depending on their texture when cooked: firm and dry or soft and moist. White sweet potatoes are usually firm and dry, while orange and purple sweet potatoes are soft and moist.

Sweet potatoes are excellent sources of carotenes. They are great sources of vitamin C and B6 and good sources of manganese, copper, biotin, vitamin B5, vitamin B2 and fibre.¹

White Potatoes

Potato (Solanum tuberosum) is a Solanaceae or nightshade family member.² Other members include aubergines, tomatoes and bell peppers. Over 100 varieties of potatoes exist, and they’re classified as either starchy or floury, waxy or new and all-purpose.  

The most popular starchy or floury potato in the U.S. is the Russet, while the Red LeSoda and Red Pontiac are popular varieties of waxy or new potatoes. In the UK, Maris Piper and King Edward are some of the most popular starchy potatoes, while the Charlotte, Jersey royal and Nicola are the most popular waxy or new potatoes. Desiree is considered all-purpose or in-between potatoes.

Potatoes are also rich in fibre, vitamin C, B vitamins and potassium and are a source of phosphorus and calcium. They contain antioxidants, including phenolic acids and polyphenols and depending on the variety, anthocyanins, which are the red, blue and purple pigments found in the skin and flesh.²

Nutritional value of Potatoes3,4
Per 100g (raw)	White potato	Sweet Potatoes
Energy (kcal)	77	86
Carbohydrates (g) Of which sugar (g)	17.5 0.82	20.1 6.06
Protein (g)	2.05	1.57
Fat (g)	0.09	0.05
Fibre (g)	2.1	3
Minerals Potassium (mg) Magnesium (mg) Calcium (mg) Iron (mg) Zinc (mg)	425 23 12 0.81 0.3	337 19.1 30 0.61 0.3
Vitamins Vitamin A (mcg) Beta-carotene (mcg) Vitamin B6 Niacin Vitamin C (mg) Folate (mcg)	– – 0.3 1.06 19.7 15	709 8510 0.21 0.56 2.4 11

Glycaemic Index – Sweet Potatoes vs. White Potatoes

The glycaemic index measures how quickly carbohydrate-rich foods raise blood sugar.⁵ Fast-digesting carbohydrates can spike blood sugars or raise them quickly and are called high-glycaemic. Moderate-digesting or medium-glycaemic carbohydrates increase blood sugars moderately while slow-digesting or low-glycaemic carbohydrates increase them slowly.⁵

The glycaemic index ranks food from 0 (low) to 100 (high). Low glycaemic foods have a score of 0-55, medium glycaemic foods have a score of 56-59, and high glycaemic foods have a rate of 70 and above.⁵ The glycaemic index of white potatoes varies according to the variety, typically due to the ratio of amylopectin and amylose starch they contain.²

Amylopectin is more filling and slower to digest, while amylose less filling and easy to digest. Floury or starchy varieties of potatoes, such as Maris piper and Russet, contain more amylose than amylopectin, making them easy to digest and high glycaemic. In contrast, new or waxy potatoes contain more amylopectin, so they digest more slowly and have a lower glycaemic index. The all-purpose potato, Desiree, is also high glycaemic even though it contains less amylose than the floury or starchy varieties.

The glycaemic index of potatoes varies depending on how you cook them. However, sweet potatoes have a lower glycaemic index than white potatoes, regardless of how you cook them. That said, the evidence for the best cooking method is conflicting. Some evidence suggests that mashed and boiled potatoes have higher glycaemic indices than fried, microwaved or baked potatoes.⁶ Other studies show that boiled sweet or white potatoes have lower glycaemic indices than their baked counterparts.⁷

Cooking Method	Glycaemic Index of Different Types of potato5,6
–	Starchy		Waxy		All-purpose	Sweet
	Maris Piper	Russet	Charlotte	Nicola	Desiree	Orange
Boiled	85	82	66	59	79	47
Baked	–	111	–	–	–	83
Fried	–	–	–	–	–	77

The Best Way to Eat Potatoes if You Have Diabetes

Boiled sweet potatoes have the lowest glycaemic index, but you can cook them how you enjoy eating them. Aim for around 200g of potatoes (raw weight) per serving and pair them with foods rich in protein, such as meat, chicken, fish and beans and healthy fats, such as olives, oils and avocados, to reduce glycaemic index and prevent blood sugar spikes, especially if baking.⁶  

Remember that frying adds extra calories and can cause weight gain if you eat a high-calorie or energy-dense diet.  

Try These Tips

• Whether white or sweet, potatoes are good vitamin C, potassium and fibre sources.
• Sweet potatoes and waxy potatoes raise blood sugar the least.
• Regardless of which potatoes you choose and how you cook them, always pair them with leafy vegetables, protein and healthy fat to prevent blood sugar spikes.

DISCLAIMER: Not a substitute for medical advice – All content is for informational purposes only and is not intended to provide medical or nutrition advice or to take the place of medical/nutrition advice or treatment from your doctor or health professional. Since each person’s health conditions are very specific, viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. All content, including text, graphics, images, and information in this post/video, is for general information only and does not replace a consultation with your doctor/health professional.

References

1. Mohanraj, R., & Sivasankar, S. (2014) Sweet potato (Ipomoea batatas [L.] Lam) – a valuable medicinal food: a review. Journal of Medicinal Food, 17 (7): 1-9.
2. Camire, M.E., Kubow, S., & Donnelly, D.J. (2009) Potatoes and human health. Critical Reviews in Food Science and Nutrition, 49 (10): 823-840.
3. Food Data Central. Sweet potato, raw, unprepared. Available: https://fdc.nal.usda.gov/fdc-app.html#/food-details/168482/nutrients. Accessed: 20 May 2023.
4. Food Data Central. Potatoes, flesh and skin, raw. Available: https://fdc.nal.usda.gov/fdc-app.html#/food-details/170026/nutrients. Accessed: 20 May 2023.
5. Augustin, L.S.A, Kendall, C.W.C., Jenkins, D.J.A., Willett, W.C., Astrup, A., Barclay, A.W., Bjorck, I., Brand-Miller, J.C., Brighenti, F., Buyken, A.E., Ceriello, A., La Vecchia, C., Livesey, G., Liu, S., Riccardi, G., Rizkalla, S.W., Sievenpiper, J.L., Trichopoulou, A., Wolever, T.M.S., Baer-Sinnott, S., & Poli, A. (2015) Glycaemic index, glycaemic load and glycaemic response: an international scientific consensus summit from the International Carbohydrate Quality Consortium (ICQC). Nutrition Metabolism and Cardiovascular Disease, 25(9): 795-815.
6. Sagili, V.S., Chakrabarti, P., Jayanty, S., Kardile, H., & Sathuvalli, V. (2022). The glycaemic index and human health with an emphasis on potatoes. Foods, 11(15): 2302.
7. Atkins, F.S., Brand-Miller, J.C., Foster-Powell, K., Buyken, A.E., Goletzke, J. (2021) International tables of glycaemic index and glycaemic load values 2021. American Journal of Clinical Nutrition, 114(5): 1625-1632.
8. Glycemic Index Research and GI News. Available: https://glycemicindex.com/gi-search-instructions/ Accessed: 19 May 2023.