I eat fruit juice blended by blender every night. I use a blender to blend Watermelon, Lychee, Melon etc. Is the sugar from the fruit a risk for diabetes?

  • Why not have your watermelon in the morning? No need to juice it. It will provide hydration, some energy, and may even reduce inflammation. Have some protein with your breakfast too. In this abstract, CVD = cardiovascular disease: heart and blood vessels.
    – Gordon
    Commented Jul 2, 2018 at 14:12
  • ncbi.nlm.nih.gov/m/pubmed/25631716
    – Gordon
    Commented Jul 2, 2018 at 14:12
  • When I was young, people had juice glasses (cups). These were really small glasses, for fruit juice. These people were very wise. If you are drinking fruit juice (pure juice) try to limit your consumption to 4oz. at a sitting.
    – Gordon
    Commented Jul 2, 2018 at 14:38
  • 1
    Do you put the entire peeled fruit, same as what you would eat if you just ate it, in the blender? do you add anything to the blender other than fruit? Commented Jul 2, 2018 at 15:23
  • 2
    That's not juicing, that is called a smoothie. Juice is when fruit is pressed and much of pulp is removed. Smoothies are known to be healthier than juice because the fiber of the fruit pulp reduces the speed of uptake of the sugars and promotes better GI health.
    – DoctorWhom
    Commented Jul 4, 2018 at 17:08

2 Answers 2


The question is about whole fruits vs blended fruits (smoothies), but I haven't found any studies about smoothies, so I included those about fruit juices. Both the smoothies and the fruit juices are liquid, so they pass the stomach faster than whole fruits, which can result in higher blood glucose spikes (a possible risk factor for diabetes). The other aspect is that smoothies probably contain about the same amount of fiber than whole fruits, while fruit juices contain much less fiber. Fiber likely decreases blood glucose spikes after meals.

Concluding from academic.oup.com, blending fruits probably does not affect the fiber in the nutritional sense:

The quantitative measurement of dietary fiber does not recognize its diverse actions on nutrient absorption...

According to 2 systematic reviews of studies, intake of 100% fruit juice (no sugar added) is not associated with diabetes type 2.

Intake of fruit juice and incidence of type 2 diabetes: a systematic review and meta-analysis (PubMed, 2014)

A higher intake of sugar-sweetened fruit juice was significantly associated with risk of type 2 diabetes, while intake of 100% fruit juice was not associated with risk of developing type 2 diabetes.

100 % Fruit juice and measures of glucose control and insulin sensitivity: a systematic review and meta-analysis of randomised controlled trials (PubMed, 2017)

Overall, findings from this meta-analysis of RCT suggest a neutral effect of 100 % fruit juice on glycaemic control. These findings are consistent with findings from some observational studies suggesting that consumption of 100 % fruit juice is not associated with increased risk of diabetes.

However, according to one 2015 systematic review:

both artificially sweetened beverages and fruit juice were unlikely to be healthy alternatives to sugar sweetened beverages for the prevention of type 2 diabetes.

And finally, according to one study, which followed nurses for 18 years: Intake of Fruit, Vegetables, and Fruit Juices and Risk of Diabetes in Women (PubMed, 2008):

Consumption of green leafy vegetables and fruit was associated with a lower hazard of diabetes, whereas consumption of fruit juices may be associated with an increased hazard among women.

  • 1
    Juice is a risk factor for weight gain, which is a risk factor for diabetes... Which is why we advise prediabetics to eat like diabetics in order to help prevent progression of their insulin resistance. Usually they are recommended to eat fruit rather than juice, so they benefit from the fiber in the pulp, and include protein sources (like almonds) to balance out the meal/snack.
    – DoctorWhom
    Commented Jul 4, 2018 at 17:11
  • I personally am convinced that sugar stimulates food craving, which could lead to unhealthy weight...but I haven't found a good study about this. They are studies about sugar + fat = food craving, but not sugar alone.
    – Jan
    Commented Jul 4, 2018 at 17:14
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    I've heard tons of presentations about these topics from field experts but don't have the primary literature at the tips of my fingers. High sugar intake --> spike in blood sugar --> spike in insulin levels = proposed mechanism for developing or worsening insulin resistance. Even anecdotally, we see many patients reduce their a1c significantly just by cutting out refined sugars and increasing fiber intake whether they lose weight or not. But a1c reflects average blood sugar concentration, not directly insulin resistance.
    – DoctorWhom
    Commented Jul 4, 2018 at 17:23
  • Yes, and from I have researched so far, the amount of sugar intake by itself is not directly associated with diabetes.
    – Jan
    Commented Jul 4, 2018 at 17:27
  • 3
    I will try to find my sources on some of the research that suggests a more direct association. But the fundamental issue is that whether the association is direct or indirect is irrelevant if a person develops diabetes - we give advice about both direct and indirect factors, to minimize ALL chances of developing/worsening the condition and its sequelae.
    – DoctorWhom
    Commented Jul 4, 2018 at 17:33


Fruit fibres help regulate sugar blood level [1].
Thank to this, if you do not just extract juice from your blender but you drink/eat to whole processed fruit, I think that will not be an issue for diabetes, or better, it has the same value of eating the same entire fruit.

What I don't know:

  1. does mastication play a role in this game?
  2. does blender break fibres? if yes, how them compare to the whole ones?

EDIT: linked answer Is it better to eat fruit as they are, than to have them in liquid form?

  • What does [WIP] mean?
    – Carey Gregory
    Commented Jul 4, 2018 at 1:29
  • Fruit juice is usually not considered a food high in fiber. The broken fiber in juice probably has less health benefits that the whole fiber in fruits.
    – Jan
    Commented Jul 4, 2018 at 16:55
  • @CareyGregory Work in Progress, I guess
    – Narusan
    Commented Jul 4, 2018 at 17:37
  • @CareyGregory yes
    – mattia.b89
    Commented Jul 4, 2018 at 23:34
  • @Jan can you provide any source?
    – mattia.b89
    Commented Jul 4, 2018 at 23:35

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