T2 Diabetes and Low-Carb Diets

"I can manage this diabetes"

"I can manage this diabetes"

Precautions and Disclaimer:  See page bottom. 

♦   ♦   ♦

Carbohydrates and Blood Sugar

Carbohydrate consumption has a major effect on blood sugar (glucose) levels—often causing a rise—in many people with type 2 diabetes. Most folks with diabetes are taking medications to lower their glucose levels.

Low-carb and very low-carb diets (often called ketogenic diets) restrict the dieter’s carbohydrate consumption rather dramatically. 

Remember that the main classes of food—macronutrients—are proteins, fats, and carbohydrates.  Common carbohydrate sources are:

  • grains
  • fruits
  • starchy vegetables (e.g., potatoes, corn, peas, beans)
  • milk products
  • candy
  • sweetened beverages
  • other added sugars (e.g., table sugar, high fructose corn syrup)

The typical American way of eating provides 250–300 grams of carbohydrate daily.   Very low-carb diets limit carbohydrates to under 50 grams daily, typically in the 20–25 gram range.  Low-carb diets provide 50 to 130 grams of carbohydrate daily.  In healthy people and mild diabetics not treated with medication, this carbohydrate restriction rarely causes low blood sugar problems (hypoglycemia).  But in other diabetics, carbohydrate restriction can lead to serious, even life-threatening, symptoms of hypoglycemia. 

Hypoglycemia is also a potential problem for diabetics on traditional balanced reduced-calorie diets

Hypoglycemia, however, is an even greater risk for diabetics taking certain diabetic medications while on a carbohydrate-restricted diet. 

Hypoglycemia:  Recognition and Management

Hypoglycemia is the biggest immediate risk for a diabetic starting a carbohydrate-restricted diet.  Hypoglycemia means an abnormally low blood sugar (under 60–70 mg/dl) associated with symptoms such as weakness, malaise, anxiety, irritability, shaking, sweating, hunger, fast heart rate, blurry vision, difficulty concentrating, or dizziness.  Symptoms often start suddenly and without obvious explanation.  If not recognized and treated, hypoglycemia can lead to incoordination, altered mental status (fuzzy thinking, disorientation, confusion, odd behavior, lethargy), loss of consciousness, seizures, and even death (rare).

Your personal physician and other healthcare team members will teach you how to recognize and manage hypoglycemia.  Immediate early stage treatment involves ingestion of glucose or other carbohydrate: six fl oz (180 ml) sweetened fruit juice, 12 fl oz ( 360 ml) milk, four tsp (20 ml) table sugar mixed in water, four fl oz (120 ml) soda pop, candy, glucose tablets or paste, etc.  Fifteen to 30 grams of glucose or other carbohydrate should do the trick.  Hypoglycemic symptoms respond within 20 minutes.

If level of consciousness is diminished such that the person cannot safely swallow, he will need a glucagon injection.  Non-medical people can be trained to give the injection under the skin or into a muscle.  Ask your doctor if you are at risk for severe hypoglycemia.  If so, ask him for a prescription so you can get an emergency glucagon kit from a pharmacy.

Do not assume your sugar is low every time you feel a little hungry, weak, or anxious.  Use your home glucose monitor for confirmation when able.  If you do experience hypoglycemia, discuss management options with your doctor: downward medication adjustment, eating more carbohydrates, shifting meal quantities or times, adjustment of exercise routine, etc.  Eating at regular intervals three or four times daily helps prevent hypoglycemia.  Spreading carbohydrate consumption evenly throughout the day also helps.  Someone most active during daylight hours as opposed to nighttime will generally do better eating carbs at breakfast and lunch rather than concentrating them at bedtime.   

Diabetics considering or following a low-carb or very low-carb ketogenic diet must work closely with their personal physician and dietitian, especially to avoid hypoglycemia.  Clinical experience with thousands of patients has led to generally accepted guidelines. 

Diabetics not being treated with pills or insulin rarely need to worry about hypoglycemia.  Similarly, diabetics treated only with diet, metformin, colesevalam, and/or an alpha-glucosidase inhibitor (acarbose, miglitol) should not have much, if any, trouble with hypoglycemia.  The DPP4-inhibitors (sitagliptan and saxagliptin) do not seem to cause low glucose levels, whether used alone or combined with metformin or a thiazoladinedione. 

Thiazolidinediones by themselves cause hypoglycemia in only 1 to 3% of users, but might cause a higher percentage in people on a reduced calorie diet. As of January 9, 2010, I’m not sure if bromocriptine by itself causes hypoglycemia: I suspect not, but check with your own doctor or pharmacist.

People who don’t know the class of their diabetic medication should ask their physician or pharmacist. 

Type 2 diabetics are at risk for hypoglycemia if they use the following drug classes 

  • insulin
  • sulfonylureas: glipizide, glyburide, glimiperide, chlorpropamide, acetohexamide, tolbutamide
  • meglitinides: repaglinide, nateglinide
  • pramlintide plus insulin
  • exenatide plus sulfonylurea
  • and possibly thiazolidinediones: pioglitazone, rosiglitazone

Common management strategies for diabetics on these drugs and starting a very low-carb ketogenic diet include:  

  • reduce the insulin dose by half
  • change short-acting insulin to long-acting (such as glargine)
  • stop the sulfonylurea, or reduce dose by half
  • reduce the thiazolidinedione by half
  • stop the meglitinide, or reduce the dose by half
  • monitor blood sugars frequently, such as four times daily, at least until a stable pattern is established
  • spread what few carbohydrates are eaten evenly throughout the day

Management also includes frequent monitoring of glucose levels with a home glucose monitor, often four to six times daily.  Common measurement times are before meals and at bedtime.  It may be helpful to occasionally wake at 3 AM and check a sugar level.  To see the effect of a particular food or meal on glucose level, check it one or two hours after eating.  When eating patterns are stable, and blood sugar levels are reasonable and stable, monitoring can be done less often.  When food consumption or exercise habits changes significantly, check sugar levels more often.   

If you’re thinking that many type 2 diabetics on low-carb and very low-carb ketogenic diets use fewer diabetic medications, you’re right.

Steve Parker, M.D.

Precautions and Disclaimer:  The ideas and suggestions in this document are provided as general educational information only and should not be construed as medical advice or care.  Information herein is meant to complement, not replace, any advice or information from your personal health professional.  All matters reagarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status.  Always consult your personal physician before making any dietary, nutritional supplement, or exercise changes.  Steve Parker, M.D., pxHealth, and Vanguard Press disclaim any liability or warranties of any kind arising directly or indirectly from use of this document.  If any problems develop, always consult your personal physician.  Only your physician can provide you medical advice.   

Last updated January 9, 2010 

12 responses to “T2 Diabetes and Low-Carb Diets

  1. Eat the FOODS you WANT but STILL LOSE WEIGHT!
    – A program where you will have a “Burn Days” and “Feed Days”.
    – A very different program that others has.
    – This will surely work for you if you will not hesitate to discover the secret to permanent weight lose!!

  2. pjnoir

    What crap- Low carb diets reduce the need for meds which is a goal with a low carb diet. Fearing hypoglycemia on a low carb diet is like the fear of lightening while sitting in the house on a sunny day. Type 2s would live far healthier lives by reducing carbs, getting off the wheat addiction and using less harmful( in the long run) meds.

  3. Snackman

    Diabetes is a dangerously high level of blood sugar caused by excessive sugar (carb) consumption. Diabetics inject insulin to lower their blood sugar. Hypoglycemia is caused by a combination of too much insulin, too much exercise and too little carbs. So do we limit exercise and increase carbs to avoid hypoglycemia? Not hardly. If diabetics eat low carb and exercise, they will NATURALLY reduce their blood sugar levels while also reducing their need to inject insulin. So all they need to do to avoid hypoglycemia is to cut down on insulin injections. This is simply common sense, and practical experience tells us that Low Carb and exercise is the only approach that works for diabetics – and they lose weight as well.

  4. jill tompkins

    i need to know what to eat that burns fat the rest i can do my self

  5. yanira j caceres

    I am a tipe 2 diabetic person 42 years old, and I am interested in having some recipies for low carb foods.

  6. louise mollot-dicicco

    FOR PAST 20 years-when i eat fruit or MILK,any sweet veg or sweet nuts like almonds,cashews or white rice-OR CITRIC ACID or vitamin,minerals that have additives (w name that ends with -ose or -ol or -ate)-then always 2 DAYS LATER i get severe migraine which lasts 2 days IN BED-during which i am forced to fast even water i vomit up- 3rd day i feel just great-even tho not eaten for 2 days-my question is: why always 2 days between whenn i eat sweet things, and the start of my migraines– MY DOCS SAY MY GLUC TOLERANCE TEST IS NORMAL-i got glucose reader-up hight to 11.8 and 12.4- then lo to 3.9 mmol- but why the 2 day delay in my reaction migraines to sweets

  7. Annie Lin

    Thank you Dr. Parker for this very informative article. I read many LCHF articles but few explain how to manage diabetes medication while incorporating or transitioning to LC meals. My husband was diagnosed with T2 after his liver disease. Since then he’s had a liver transplant and his insulin dosages have decreased significantly, however not completely. I have the goal of reversing his diabetes once and for all! Right now he is taking Onglyza (saxagliptin), 8 units Tresiba in the morning, and between 0-1-2 units of Novolog at meals (depending on carb portion). What would you suggest he weans off first? His doctor recommended weaning from Tresiba first in 1 unit increments (while monitoring fasting blood sugar levels), then when its completely not needed the short acting insulin, and lastly the oral medication Onglyza. His doctor is good but does not have expertise in NK or LCHF diets. I just want to make sure any medication he is on, which encourages glucose breakdown, will not counter with our goal of breaking downs fats for fuel instead. Any help would be appreciated! Thank you.

    • I think his doctor is on the right track. As you probably know, the biggest risk of a dramatic reduction of dietary carbohydrates is hypoglycemia. In the scientific studies of low-carb diets in diabetics (e.g., switching from the usual 250 grams/day to 50 or less), many participants needed a 25-50% reduction in insulin (and other drugs that cause hypoglycemia) right off the bat. Use that home glucose monitor frequently, especially early-on (e.g., four times a day, or more). I’m glad to know your husband’s insulin doses are relatively low now. Onglyza by itself rarely, if ever, causes hypoglycemia. Good luck to you both!
      -Steve

  8. Ayeen

    Thank you Dr. Parker for this very informative article. I read many LCHF articles but few explain how to manage diabetes medication while incorporating or transitioning to LC meals. My husband was diagnosed with T2 after his liver disease. Since then he’s had a liver transplant and his insulin dosages have decreased significantly, however not completely. I have the goal of reversing his diabetes once and for all! Right now he is taking Onglyza (saxagliptin), 8 units Tresiba in the morning, and between 0-1-2 units of Novolog at meals (depending on carb portion). What would you suggest he weans off first? His doctor recommended weaning from Tresiba first in 1 unit increments (while monitoring fasting blood sugar levels), then when its completely not needed the short acting insulin, and lastly the oral medication Onglyza. His doctor is good but does not have expertise in NK or LCHF diets. I just want to make sure any medication he is on, which encourages glucose breakdown, will not counter with our goal of breaking downs fats for fuel instead. Any help would be appreciated! Thank you.

  9. Stub

    Can u eat sushi on this diet

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