Fruit and Diabetes: What's the Link?

Dr. William Davis Health Pro
  • Mitch felt fine. At 5 ft 7 inches, he weighed a comfortable 159 lb, though he did have a small visible "paunch" above his beltline. Mitch was active every day, walking, biking, and taking care of his home and lawn.


    I had been seeing Mitch for his high heart scan score of 1157 caused by low HDL (38 mg/dl), an excess of small LDL particles (87% of total LDL), and the inherited abnormality, lipoprotein(a) (Lp(a).


    Part of Mitch's therapeutic program was elimination of wheat, cornstarch, and sugars, the three most flagrant triggers of small LDL particles, and weighing his diet in favor of oils and fats to reduce Lp(a). However, Mitch somehow failed to follow my restriction on fruit, which we limit to no more than two 4 oz servings per day, preferably berries. (I impose a restriction on fruit because of sugar content and causing formation of small LDL particles.) He thought I said "Eat all the fruit you want." And so he did.

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    Mitch had a banana, orange, and blueberries for breakfast. For lunch, along with some tuna or soup, he'd typically have half a melon, a pear, and red grapes. For snacks, he'd have an apple or nectarine. After dinner, it wasn't unusual for Mitch to have another piece of fruit for dessert.


    Up until Mitch's last visit, he'd had (fasting) blood glucose levels of 100-112 mg/dl, mildly above normal and reflecting insulin resistance and pre-diabetes. Today, on his unlimited fruit diet, his fasting blood sugar: 166 mg/dl: Mitch was diabetic.


    I helped Mitch understand the principles of diet better and advised him to reduce his fruit intake to no more than the two small servings per day, as well as sticking to my "no wheat, no cornstarch, no sugar" principles.


    While fruit is certainly better than, say, a half-cup of gummy bears (84.06 g carbohydrates, 50.12 g sugars), fruit is unavoidably high in carbohydrates and sugars.


    Take a look at the carbohydrate content of some common fruits:


    Apple, 1 medium (2-3/4" diameter)

    19.06 g carbohydrate (14.34 g sugar)


    Banana, 1 medium (7" to 7-7/8" long)

    26.95 g carbohydrate (14.43 g sugar)


    Grapes, 1 cup

    27.33 g carbohydrate (23.37 g sugar)


    Pear, 1 medium

    25.66 g carbohydrate (16.27 g sugar)


    Source: USDA Food and Nutrient Database


    By eating large quantities of fruit every day, Mitch increased his carbohydrate and sugar intake by over 150 grams per day, sufficient to push blood sugars up over 50 mg/dl into the diabetic range, as well as worsen his hidden small LDL pattern.


    Fruit has many healthy components, of course, such as fiber, flavonoids, and vitamin C. But it also comes with plenty of sugar. This is especially true of modern cultivated fruit, the sort that has been fertilized, hybridized, gas-treated, etc. for size and sugar content.


    When you hear conventional advice like "eat plenty of fruits and vegetables," you should hear instead: "Eat plenty of vegetables. Eat a small quantity of fruit."


Published On: February 12, 2010