It depends on the variety, cooking method, and how you eat them. Boiled waxy potatoes (GI 56–69) cause significantly less blood sugar rise than baked Russet Burbank (GI 85–111). Cooling cooked potatoes for 24 hours forms RS3 resistant starch and reduces postprandial glycemic response by 25–35%(Raatz et al., 2016; Leeman et al., 2005). The American Diabetes Association lists potatoes as an acceptable food when portion-controlled, and peer-reviewed evidence shows the picture is far more nuanced than “potatoes spike blood sugar.” Variety, cooking method, and accompaniments matter more than avoiding potatoes outright.
In this article (8 sections)▾
What is the glycemic index of potatoes?
The glycemic index (GI) measures how quickly a food raises blood glucose, on a scale of 0–100 with pure glucose set to 100. Anything under 55 is low, 56–69 is medium, and 70+ is high. Potatoes occupy an unusually wide range — from a Carisma at GI 53 all the way up to a baked Russet Burbank at GI 111 — depending on variety, cooking method, and how recently the potato was cooked.
The full picture, drawn from the University of Sydney GI Database (Atkinson et al., 2008, Diabetes Care; Foster-Powell et al., 2002, American Journal of Clinical Nutrition) and peer-reviewed cooling studies (Leeman et al., 2005), is below. Glycemic load (GL) — which scales GI by typical serving carbohydrate content — tells you how much actual glucose your meal delivers, and is the more practical metric for portion control.
| Potato Type / Method | GI | Classification | GL per Serving | Notes |
|---|---|---|---|---|
| Boiled waxy / new potato | 56–69 | Medium | 12–14 | Lowest GI hot preparation |
| Boiled white potato (floury) | 78–101 | High–Very High | 20–24 | Russet Burbank ~78–101 |
| Baked potato (Russet) | 85–111 | Very High | 26–29 | Highest GI of any preparation |
| Mashed potato | 83–88 | High | 17–22 | Starch fully gelatinized |
| French fries | 63–75 | Medium–High | 16–22 | Fat slows gastric emptying |
| Roasted potato | 70–80 | High | 18–22 | Similar to baked, slightly lower |
| Cooled boiled potato (potato salad) | 54–58 | Low–Medium | 10–13 | Resistant starch lowers GI |
| Carisma (low-GI variety) | 53 | Low | 10–12 | Bred for low GI; registered claim |
| Instant mashed potato | 83–88 | High | 17–22 | Highly processed, fast digestion |
| Potato chips / crisps | 51–60 | Medium | 10–14 | High fat slows absorption |
| Sweet potato (for comparison) | 44–61 | Low–Medium | 10–14 | Different botanical species |
Source: International Tables of Glycemic Index and Glycemic Load Values (Atkinson et al., 2008, Diabetes Care; Foster-Powell et al., 2002, American Journal of Clinical Nutrition); University of Sydney GI Database; Leeman et al. (2005), European Journal of Clinical Nutrition.
The single most actionable insight here: GI varies by 2x for the same potato depending on how you cook it. A Russet Burbank baked plain rates GI 85–111 (very high). Cooled and made into potato salad with vinaigrette, the same tuber drops to GI 54–58 (low–medium). The variety in your hand is less important than the cooking and cooling decisions you make in the kitchen.
How does cooking method affect blood sugar response?
Starch granules in raw potato are tightly packed semi-crystalline structures that human digestion can't access. Cooking gelatinizes the starch — granules absorb water, swell, and become digestible. The further this gelatinization goes, the higher the GI. The table below summarizes how each common method shifts blood sugar response.
| Method | Effect on GI | Mechanism |
|---|---|---|
| Boiling | Lower (56–101) | Granules less gelatinized; faster cooling option |
| Baking | Higher (85–111) | Full gelatinization; dry heat fluffs starch |
| Frying | Moderate (63–75) | Fat slows gastric emptying |
| Cooling 24h after cooking | −10 to −15 points | Forms RS3 retrograded starch |
| Reheating cooled potato | Retains 50–70% benefit | Most RS3 survives moderate heat |
| Adding vinegar / lemon | −20 to −30% | Acid slows gastric emptying |
Source: Atkinson et al. (2008); Leeman et al. (2005); Fernandes et al. (2005), Journal of the American Dietetic Association.
Boiling keeps starch granules more intact than dry-heat methods because water saturates the tuber from outside in, leaving the core less fully gelatinized. Baking gelatinizes starch fully and concentrates sugars as moisture evaporates, producing the highest hot-eaten GI of any preparation. Frying sits in the middle: starches gelatinize, but the fat coat slows gastric emptying enough to moderate the response — this is also why French fries score lower than a plain baked potato. Eating with fat, protein, or acid shifts GI down further: a vinaigrette dressing on potato salad reduces GI by 20–30% via slowed gastric emptying.
What is resistant starch and why does it matter?
Resistant starch (RS) is starch that escapes digestion in the small intestine and arrives intact in the colon, where gut bacteria ferment it. It behaves nutritionally like dietary fiber. There are four types:
RS1 — physically protected starch (whole grains, intact seeds). RS2 — raw resistant granules (raw potato, green banana). RS3 — retrograded starch: cooked starches that re-crystallize on cooling. RS4 — chemically modified industrial starch.
The RS3 in cooled cooked potatoes is the type that matters here. Hot freshly-cooked potato contains roughly 0.6 g RS per 100 g; the same potato cooked, cooled at 4–8°C for 24 hours, and eaten cold contains roughly 2.4 g RS per 100 g — a 4x increase. Leeman et al. (2005, European Journal of Clinical Nutrition) measured a 25% lower glycemic index in 24-hour cooled potatoes versus the same potatoes eaten hot. Raatz et al. (2016, Journal of the Academy of Nutrition and Dietetics) found postprandial glucose response reduced by 25–35%.
Reheating partially preserves the benefit. Fernandes et al. (2005, Journal of the American Dietetic Association) found that gently reheated cooled potato retained 50–70% of the cooling benefit for blood sugar control. RS3 is more thermally stable than RS2 because the retrograded amylose double helices melt at higher temperatures. Practical translation: cook potatoes ahead, refrigerate overnight, eat cold or warm gently — do not microwave to 100°C.
The downstream effect is bacterial. Gut microbiota ferment RS3 into short-chain fatty acids (SCFAs), particularly butyrate. Phillips et al. (1995, American Journal of Clinical Nutrition) found that 30 g/day RS3 from retrograded potato increased fecal butyrate concentrations by 38%. Butyrate is the preferred energy source of colonocytes and has documented anti-inflammatory effects on the gut lining. Eating cooled potato isn't just lower-GI — it actively feeds the part of the digestive tract that benefits from prebiotic fiber.
Which potato varieties have the lowest glycemic index?
The amylose-to-amylopectin ratio of a variety's starch determines digestibility. Higher amylose = more resistant to digestion = lower GI. Waxy varieties (Type A in European cooking-type terminology) have higher amylose and lower GI. Floury varieties (Type C–D) have lower amylose and higher GI. The Australian-bred Carisma was specifically selected for low GI and is one of the only potatoes with a registered low-GI claim.
| Variety | Cooking Type | GI (boiled) | Best For |
|---|---|---|---|
| Nicola | Waxy (Type A) | 56–62 | Salads, boiling — lowest hot-eaten GI |
| Charlotte | Waxy (Type A) | 58–65 | Salads, gentle boiling |
| Carisma | Low-GI bred | 53 | Specifically registered as low-GI |
| Kipfler / fingerling | Waxy | 60–68 | Roasting, salads |
| Yukon Gold | All-purpose | 70–78 | Versatile mid-GI option |
| Désirée | All-purpose | 70–78 | Boiling, mash, salads |
| Maris Piper | Floury | 85–95 | Roasting, fries |
| Russet Burbank | Floury | 85–111 | Baking, frying — highest GI |
Source: University of Sydney GI Database; Atkinson et al. (2008); Foster-Powell et al. (2002). Also see our Russet Burbank history for context on the highest-GI commercial variety.
Can diabetics eat potatoes?
Yes — the American Diabetes Association does not prohibit potatoes; it recommends portion control plus smart preparation. The standard carbohydrate exchange is 1/2 cup (75 g) of cooked potato, which delivers approximately 15 g carbohydrate. Most adults with type 2 diabetes can include 1–2 carbohydrate exchanges per meal within their overall plan, especially when paired with non-starchy vegetables and protein. See our detailed diabetic potato guide.
Five high-impact strategies the ADA and peer-reviewed evidence support: (1) Choose waxy varieties (Nicola, Charlotte, Carisma) over floury ones (Russet Burbank, Maris Piper). (2) Boil rather than bake. (3) Cool cooked potatoes for 24 hours before eating — the resistant-starch effect compounds with all other strategies. (4) Pair with protein, healthy fat, and vinegar or lemon. (5) Stick to the 75 g (1/2 cup) carb exchange portion.
It's also worth keeping perspective: glycemic index is not the only thing that matters. White rice has a GI of 73 and white bread 75 — both close to a boiled potato. A medium boiled potato has a glycemic load of 12–14, while a typical white-rice serving has GL ~29. Combined with potato's 620 mg potassium, 27 mg vitamin C, and 4.7 g fiber per medium tuber (USDA FoodData Central), the nutritional package compares favorably with refined grains. Potato vs rice for blood sugar is closer than common wisdom suggests.
Are potatoes healthy despite the blood sugar concern?
For most people, yes. A medium baked potato (150 g, with skin) provides 110 calories, 620 mg of potassium (18% DV — more than a banana), 27 mg of vitamin C (30% DV), 4.7 g of fiber, 3 g of protein, and 0 g of fat (USDA FoodData Central). Potatoes are naturally gluten-free, cholesterol-free, and rank #1 on the Satiety Index — Holt et al. (1995, European Journal of Clinical Nutrition) found that boiled potatoes scored 323% on satiety, 3.2x more filling than white bread (set at 100%).
High satiety matters more than glycemic index alone for everyday weight and metabolic management. People who feel full eat less; lower total calorie intake reduces blood sugar excursions across the day regardless of what triggered each individual meal. Coloured varieties (Purple Majesty, Adirondack Blue) add anthocyanins with documented anti-inflammatory effects.
The genuine concern is not the potato itself — it's preparation and quantity. A 300 g pile of fries with butter, sour cream, salt, and a beer is a metabolic load problem. A 150 g boiled new potato with vinaigrette and protein is not. Potato nutrition facts covers the full nutrient picture in detail.
What does the latest research say?
The recent evidence base has shifted toward nuance. Earlier work like the Harvard Nurses' Health Study found an association between high baked-potato and French-fry consumption and increased type 2 diabetes risk — but did not separate cooking method, cooling, or accompaniments. Updated meta-analyses with better stratification have found moderate consumption (3–5 servings per week) of boiled or cooled potatoes is not associated with increased T2D risk, and may even be neutral-to-protective in Nordic populations where boiled potatoes are a traditional staple.
Australian work on the Carisma low-GI variety showed a 20% reduction in postprandial glucose excursion versus standard Désirée potato. The Raatz et al. (2016) cooling study replicated the 25–35% glucose reduction across multiple varieties and cooling regimes. Phillips et al. (1995) confirmed the colonic butyrate benefit. Together, these findings support a clear practical conclusion: cooking method and overall dietary pattern matter more than the question of whether to eat potatoes at all.
For a concise summary of the diabetic-potato evidence, see our diabetic potato FAQ, the nutrition page, and the country profiles for high-potato-consumption nations like the United States, United Kingdom, Germany, Peru, India, China, Bangladesh, and Australia.
Frequently Asked Questions
Do potatoes spike blood sugar?+
It depends on the variety and cooking method. Boiled waxy potatoes (GI 56–69) cause a moderate response; baked Russet Burbank (GI 85–111) causes a high spike. Cooling cooked potatoes for 24 hours at 4–8°C forms RS3 retrograded starch and reduces postprandial glycemic response by 25–35% (Raatz et al., 2016; Leeman et al., 2005).
Are potatoes bad for diabetics?+
The American Diabetes Association lists potatoes as acceptable when portion-controlled. Choose waxy varieties, boil rather than bake, cool the cooked potato before eating, pair with protein or vinegar, and stick to a 1/2-cup (75g) serving = ~15g carbohydrate per carb exchange. Glycemic load matters more than glycemic index alone.
Which potato has the lowest glycemic index?+
Waxy varieties such as Nicola, Charlotte, and Kipfler boil at GI 56–69. The purpose-bred Carisma variety registers GI 53 — the lowest of any commercially available potato. Cooling any boiled potato for 24 hours reduces its GI by 10–15 points further.
Does cooling potatoes lower blood sugar impact?+
Yes. Leeman et al. (2005) showed that boiled potatoes stored at 8°C for 24 hours had a 25% lower glycemic index than freshly boiled potatoes. The cooling process retrogrades amylose into RS3 — resistant starch that resists enzymatic digestion and is fermented by gut bacteria into butyrate. Reheating retains 50–70% of the benefit (Fernandes et al., 2005).
Are sweet potatoes better than regular potatoes for blood sugar?+
Sweet potatoes (GI 44–61) have a lower GI than baked white potatoes (GI 85–111) but are similar to boiled waxy white potatoes (GI 56–69). The difference is smaller than commonly assumed. Both are nutrient-dense and acceptable for diabetics with portion control.
How many potatoes can a diabetic eat per day?+
The American Diabetes Association suggests 1/2 cup (75g) cooked potato as one carbohydrate exchange (~15g carbohydrate). Most diabetics can include 1–2 servings per day within a balanced meal plan, especially using waxy varieties, boiled and cooled, paired with protein and vegetables.