Tag Archives: triglycerides

January 8, 2014 · 2:33 AM

Low-Carb Diet Improves Glucose Control in Japanese Type 2 Diabetics

Mt. Fuji in Japan

Mt. Fuji in Japan

I don’ know anything about Japanese T2 diabetes. I’ve never studied it. Their underlying physiology may or may not be the same as in North American white diabetics, with whom I am much more familiar.

For what it’s worth, a small study recently found improvement of blood sugar control and triglycerides in those on a carbohydrate restricted diet versus a standard calorie-restricted diet.

Only 24 patients were involved. Half were assigned to eat low-carb without calorie restriction; the other half ate the control diet. The carbohydrate-restricted group aimed for 70-130 grams of carb daily, while eating more fat and protein than the control group. The calorie-restricted guys were taught how to get 50-60% of calories from carbohydrate and keep fat under 25% of calories. At the end of the six-month study, the low-carbers were averaging 125 g of carb daily, compare to 200 g for the other group. By six months, both groups were eating about the same amount of calories.

Average age was 63. Body mass index was 24.5 in the low-carb group and 27 in the controls. (If you did the research, I bet you’d find Japanese T2 diabetics have lower BMIs than American diabetics.) All were taking one or more diabetes drugs.

The calorie-restricted group didn’t change their hemoglobin A1c (a standard measure of glucose control) from 7.7%. The low-carb group dropped their hemoglobin A1c from 7.6 to 7.0% (statistically significant). The low-carb group also cut their triglycerides by 40%. Average weights didn’t change in either group.

Bottom Line

This small study suggests that mild to moderate carbohydrate restriction helps control diabetes in Japanese with type 2 diabetes. The improvement in hemoglobin A1c is equivalent to that seen with initiation of many diabetes drugs. I think further improvements in multiple measures would have been seen if carbohydrates had been restricted even further.

Steve Parker, M.D.

Link to reference.

h/t Dr Michael Eades

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February 12, 2013 · 7:32 AM

Once Again, Low-Carbohydrate Ketogenic Diet Beats Low-Calorie For Overweight Diabetes

Kuwait City and Towers

Kuwait City and Towers

A low-carbohydrate ketogenic diet is safe, effective, and superior to a low-calorie diet in type 2 diabetics, according to a report last year in Nutrition.

Kuwaiti researchers gave 102 adult overweight diabetic men and women their choice of diet: 78 chose ketogenic, 24 went low-calorie.  Average age was 37, average weight 211 lb (96 kg).  The study lasted six months.  The ketogenic diet was very much Atkins-style, starting out at 20 grams of carbohydrate daily.  Once good weight-loss progress was made, and if carb cravings were an issue, dieters could increase their carbs in small increments weekly.

This is all they said about the low-calorie diet: “Participants in the low-calorie diet group were given appropriate guidelines and a sample low-calorie diet menu of 2200 calories is presented in Table 1” (it’s typical and reasonable).

What Did They Find?

The low-carb ketogenic dieters lost 12% of body weight, compared to 7% lost by the low-calorie dieters.  Furthermore, the ketogenic dieters showed significant lowering of total cholesterol, LDL cholesterol (bad cholesterol), and triglycerides.  HDL cholesterol (good cholesterol) rose.  The low-calorie dieters seem to have had a significant drop in LDL cholesterol, but no changes in the other lipids.

Fasting blood sugar levels dropped significantly in both groups, but more in the ketogenic dieters.  Both groups started with fasting blood sugars around 162 mg/dl (9 mmol/l) and fell to 108 mg/dl (6 mmol/l) in the ketogenic group and to 126 mg/dl (7 mmol/l) in the low-calorie group.

Glycosylated hemoglobin (hemoglobin A1c) levels fell in both groups, more so in the ketogenic dieters.  The drop was statistically significant in the ketogenic group, but the authors were unclear about that in the low-calorie dieters.  It appears hemoglobin A1c fell from 7.8% to 6.3% with the ketogenic diet (the units given for glycosylated hemoglobin were stated as mg/dl).  In the low-calorie dieters, hemoglobin A1c fell from 8.2 to 7.7%.

What’s Odd About This Study?

The title of the research report indicates a study of diabetics, but only about 25% of study participants had diabetes (total subjects = 363).  (The figures I share above are for the diabetics only.)

Glycosylated hemoglobin, a test of overall diabetes control, is reported in Fig. 1 in terms of mg/dl.  That’s nearly always reported as a percentage, not mg/dl.  Misprint?

None of the participants dropped out of the study.  That’s incredible, almost unbelievable.

The low-calorie diet was poorly described.  Were 140-lb women and 250-lb men all put on the same calorie count?

Food diaries were kept, but the authors report nothing about compliance and actual food intake.

Clearly, some of these diabetics were on insulin and other diabetic drugs.  The authors note necessary reductions in drug dosages for the ketogenic group but don’t say much about the other dieters.  They imply that the drug reductions in the low-calorie group were minimal or nonexistent.

Grand Mosque of Kuwait

Grand Mosque of Kuwait

So What?

Calorie-restricted diets are effective in overweight type 2 diabetics, but ketogenic diets are even better.

The effectiveness and safety of ketogenic diets for overweight type 2 diabetics has been demonstrated in multiple other populations, so this study is not surprising.  We’ve seen these lipid improvements before, too.

The favorable lipid changes on low-carb ketogenic diets would tend to reduce future heart and vascular disease.

I know little about Kuwaiti culture and genetics.  Their contributions to the results here, as compared with other populations, is unclear to me.  Type 2 diabetes is spreading quickly through the Persian Gulf, so this research may have wide applicability there.

Steve Parker, M.D.

Reference:  Hussain, Talib, et al.  Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes.  Nutrition, 2012; 28(10): 1016-21. doi: 10.1016/j.nut.2012.01.016

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June 25, 2010 · 2:00 AM

Seminal Paper: Carbohydrate Restriction for Type 2 Diabetes and Metabolic Syndrome

Carbohydrate-restricted eating is slowly gaining mainstream acceptance as treatment for type 2 diabetes and metabolic syndrome.  I thought it would be useful to present one of the watershed reports that summarize the potential benefits.  The article is from 2008.  Among the co-authors are some of the brightest names in this field: Richard K. Bernstein, Annika Dahlqvist, Richard Feinman, Eugene J. Fine, Robert Lustig, Uffe Ravnskov, Jeff Volek, Eric Westman, and Mary C. Vernon.

ResearchBlogging.orgThese are not wild-eyed, bomb-throwing radicals.  They are on faculty at some of the best institutes of higher learning.  They note that while many of the national diabetes organizations downplay the benefits of carb restriction, we have enough evidence now to warrant careful reconsideration.

Here are some of their major points, all backed up by references (68) from the scientific literature:

  1. Glucose (blood sugar) is a “major control element,” whether directly or indirectly through insulin, in glycogen metabolism, production of new glucose molecules, and in formation and breakdown of fat.
  2. The potential adverse effects of dietary fat are typically seen with diets high in carbohydrate.
  3.  Carb restriction improves control of blood sugars, a major target of diet therapy.  Many of the supportive studies were done with overweight or obese people (85% of type 2 diabetics are overweight).  Very low-carb diets are often so effective that diabetic medications have to be reduced at the outset of the diet. 
  4. For weight loss, carb-restricted diets work at least as well as low-fat diets.  They are usually superior. 
  5. Carb-restricted diets usually replace carbs with fat, resulting in improve markers for cardiovascular disease (lower serum triglycerides and higher HDL cholesterol levels). Replacing dietary fat with carbohydrate—the goal of many expert nutrition panels over the last 40 years—tends to increase the amount of artery-damaging “small, dense LDL cholesterol” in most of the population. 
  6. Carbohydrate restriction improves all five components of the metabolic syndrome: obesity, low HDL cholesterol, high triglycerides, high blood pressure, elevated blood sugar.
  7. Beneficial effects of carbohydrate restriction seem to occur even without weight loss. 
  8. Still worried about excessive fat consumption?  Many low-carb dieters demonstrate a significant increase in the percentage of total calories from fat, but without an increase in the absolute amount of fat eaten.  That’s because they simply reduced their total calories by reducing carb consumption. 

This post was chosen as an Editor's Selection for ResearchBlogging.orgThe authors in 2008 called for a widespread reappraisal of carbohydrate restriction for type 2 diabetes and metabolic syndrome.  It’s been happening, and many patients are reaping the benefits.

Steve Parker, M.D.

Reference: Accurso A, Bernstein RK, Dahlqvist A, Draznin B, Feinman RD, Fine EJ, Gleed A, Jacobs DB, Larson G, Lustig RH, Manninen AH, McFarlane SI, Morrison K, Nielsen JV, Ravnskov U, Roth KS, Silvestre R, Sowers JR, Sundberg R, Volek JS, Westman EC, Wood RJ, Wortman J, & Vernon MC (2008). Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome: time for a critical appraisal. Nutrition & metabolism, 5 PMID: 18397522

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May 17, 2010 · 12:22 AM

Low-Carb Mediterranean Diet Improves Glucose Control and Heart Risk Factors in Overweight Diabetics

In overweight type 2 diabetics, a low-carbohydrate Mediterranean diet improved HDL cholesterol levels and glucose control better than either the standard Mediterranean diet or American Diabetes Association diet, according to Israeli researchers reporting earlier this year.

Background

Prior studies suggest that diets rich in monounsaturated fatty acids (olive oil, for example) elevate HDL cholesterol and reduce LDL cholestrol and triglycerides in type 2 diabetics.

Low-carb diets improve blood sugar levels and reduce excess body weight in type 2 diabetics, leading to the ADA’s allowance in 2008 of a low-carbohydrate diet as an alternative to standard diabetic diets.

Many—probably most—type 2 diabetics have insulin resistance:  the body’s cells that can remove sugar from the bloodstream are not very sensitive to the effect of insulin driving sugar into those cells.  They “resist” insulin’s effect.  Consumption of monounsaturated fatty acids  improves insulin sensitivity.  In other words, insulin is better able to push blood sugar into cells, removing it from the bloodstream.

Previous studies have shown that both low-carb diets and the Mediterranean diet reduce after-meal elevations in blood sugar, which likely lowers levels of triglycerides and LDL cholesterol.

How Was the Study Done?

The goal was to compare effects of three diets in overweight type 2 diabetics in Israel over the course of one year.  Study participants totalled 259.  Average age was 56, average weight 86 kg (189 lb), average hemoglobin A1c 8.3%, and average fasting plasma glucose (sugar) was 10.3 mmol/L (185 mg/dl).  [Many diabetics in the U.S. fit this profile.]  People taking insulin were excluded from the study, as were those with proliferative diabetic retinopathy—no reasons given. 

Participants were randomly assigned to one of three diets, so there were about 85 in each group.  [Over the course of one year, people dropped out of the study for various reasons, leaving each group with about 60 subjects.] 

Here are the diets:

  • 2003 ADA (American Diabetes Association) diet:  50-55% of total caloric intake from carbohydrate (mixed glycemic index carbs), 30%  from fat, 20% from protein
  • Traditional Mediterranean (TM):  50-55% low-glycemic-index carbs, 30% fat—high in monounsaturated fat, 15-20% protein
  • Low-carb Mediterranean (LCM) :  35% low-glycemic-index carbs, 45% fat—high in monounsaturated fat, 15-20% protein

Patients were followed-up by the same dietitian every two weeks for one year.  All were advised to do aerobic exercise for 30-45 minutes at least three days a week.

Olive oil is traditionally the predominant form of fat in the Mediterranean diet and is a particularly rich source of monounsaturated fat.  At no point in this report was olive oil mentioned, nor any other source of monounsaturated fat.  Until I hear otherwise, I will assume that olive oil was the major source of monounsaturated fat in the TM and LCM diets. 

 All diets were designed to provide 20 calories per kilogram of body weight. 

In all three diets, saturated fat provided 7% of total calories.  Monounsaturated fatty acids provided 23% of total calories in the LCM, and  10% in the other two diets.  Polyunsaturated fatty acids provided 15% of calories in the LCM, and 12% in the other two diets.  The ADA diet provided 15 grams of fiber, the TM had 30 g, and the LCM had 45 g.

Adherence to the assigned diet was assessed with a “food frequency questionnaire” administered at six months.

What Did the Researchers Find?

Average reported energy intake was similar in all three groups: 2,222 calories per day.

Monounsaturated fat intake differences were statistically significant: 14.6, 12.8, and 12.6% for the LCM, TM, and ADA diets, respectively.  Polyunsaturated fat intake differences were statistically significant: 12.9, 11.5, and 11.2% for the LCM, TM, and ADA diets, respectively.

Percentage of energy from carbs was highest for the ADA diet (45.4%), intermediate for the TM diet (45.2%), and lowest for the LCM diet (41.9%).

At the end of 12 months, all three groups lost about the same amount of weight (8-9 kg or 18-20 lb), body mass index, and waist circumference.

Hemoglobin A1c fell in all three groups, but was significantly greater for the LCM group than for the ADA diet (6.3% absolute value vs 6.7%).

Triglycerides fell in all three groups, but was significantly greater for the LCM diet compared to the ADA diet.

The LCM group achieved a significant increase (12%) in HDL cholesterol compared to the ADA diet, but not different from the TM group.

LDL cholesterol fell in all three groups, and the LCM group’s drop (25%) was clearly superior to that of the ADA diet (14%) but about the same as the TM diet (21%).

Conclusions of the Investigators

We found that an intensive community-based dietary intervention reduced cardiovascular risk factors in overweight patients with [type 2 diabetes] for all three diets.  The LCM group had improved cardiovascular risk factors compared to either the ADA or the TM groups.

Only the LCM improved HDL levels and was superior to both the ADA and TM in improving glycaemic control.

It would appear that the low carbohydrate Mediterranean diet should be recommended for overweight diabetic patients.

My Comments

There’s no way the average diabetic could replicate this low-carb Mediterranean diet without working closely with a dietitian or nutritionist.

Any superiority of this low-carb Mediterranean diet may have as much to do with the increased monounsaturated fat intake as with the reduced carb consumption.  Monounsaturated fatty acid consumption is thought to improve insulin sensitivity. 

NutritionData’s Nutrient Search Tool can give you a list of foods high in monounsaturated fat.

The Mediterranean diet and low-carb diets independently have been shown to lower after-meal glucose levels, which probably lowers LDL cholesterol and triglycerides.

I’m disappointed the dietitians were not able to achieve a lower level of carbohydrate consumption in the low-carb Mediterranean diet group.  I suspect if they had, improvements in glucose control and lipids would have been even better.  But proof awaits another day.

We saw last year an article in the Annals of Internal Medicine that showed a dramatic reduction in the need for glucose-lowering drugs in type 2 diabetics following a different low-carb Mediterranean diet over four years, compared to a low-fat American Heart Association diet.  These two studies convince me a low-carb Mediterranean diet has real life-preserving and life-enhancing potential. 

Diabetics looking for a low-carb Mediterranean diet today have several options:

If you’re aware of any other low-carb, explicitly Mediterranean-style diets, please share in the Comments section.

Steve Parker, M.D. 

References: 

Elhayany, A., Lustman, A., Abel, R., Attal-Singer, J., and Vinker, S.  A low carbohydrate Mediterranean diet improves cardiovascular risk factors and diabetes control among overweight patients with type 2 dabetes mellitus:  a 1-year prospective randomized intervention study.  Diabetes, Obesity and Metabolism, 12 (2010): 204-209.

Esposito, Katherine, et al.  Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes.  Annals of Internal Medicine, 151 (2009): 306-314.

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December 18, 2009 · 4:18 PM

Low-Carb Killing Spree Continues

The choice is clear . . . NOT

Low-fat and low-carb diets produce equal weight loss and improvements in insulin resistance but the low-carb diet may be detrimental to vascular health, according to a new study in Diabetes.

Methodology

Researchers in the the UK studied 24 obese subjects—15 female and 9 male—randomized to eat either a low-fat (20% fat, 60% carbohydrate) or low-carb (20% carb, 60% fat) diet over 8 weeks.  Average age was 39; average body mass index was 33.6.  Most of them had prediabetes.  Food intake was calculated to result in a 500 calorie per day energy deficit (a reasonable reduced-calorie diet, in other words).  Study participants visited a nutritionist every other day, and all food was provided in exact weighed portions. 

Results

Both groups lost the same amount of weight, about 7.3% of initial body weight. 

Triglycerides dropped by a third in the low-carb group; unchanged in the low-fat cohort.  Changes in total cholesterol, LDL cholesterol, and HDL changes were about the same for both groups.

Systolic blood pressure dropped about 10 points in both groups; diastolic fell by 5 in both.

“Aortic augmentation index” fell significantly in the low-fat group and tended to rise in the low-carb group.  According to the researchers, the index is used to estimate systemic arterial stiffness.  [In general, flexible arteries are better for you than stiff ones.  “Hardening-of-the-arteries,” etc.]  The low-fat group started with a AAI of 17, the low-carb group started at 12.  They both ended up in the 13-14 range. 

Peripheral insulin sensitivity improved significantly only in the low-carb group but “there was no significant difference between groups.”  No difference between the groups in hepatic (liver) insulin resistance. 

Fasting insulin levels fell about 20% in the low-fat group and about 40% in the low-carb group, a difference not reaching statistical significance (p=0.17).

The Authors’ Conclusions

This study demonstrates comparable effects on insulin resistance of low-fat and low-carbohydrate diets independent of macronutrient content.  The difference in augmentation index may imply a negative effect of low-carbohydrate diets on vascular risk.

My Comments

Yes, you can indeed lose weight over eight weeks on both low-fat and low-carb diets, if you follow them.  So diets DO work.  No surprise.

Loss of excess body fat by either method lowers your blood pressure.  No surprise.

Once again, concerns about low-carb/high-fat diets adversely affecting common blood lipids—increasing heart disease risk—are not supported.  No surprise

Hyperinsulinemia and insulin resistance are risk factors for development of diabetes and cardiovascular disease.  Results here tend to favor the low-carb diet.  I have to wonder if a study with just twice the number of test subjects would have shown a clear superiority for the low-carb diet.

The authors imply that aortic augmentation index is an important measure in terms of future cardiovascular health.  A major conclusion of this study is that a change in this index with the low-carb diet might adveresly affect heart health.  Yet they don’t bother to discuss this test much at all.  I’m no genius, but neither are the typical readers of Diabetes.  I doubt that they are any more familiar with that index than am I, and I’d never heard of it before. 

[Feel free to educate me regarding aortic augmentation index in the comment section.]

Unfortunately, many readers of this journal article and the associated news releases will come away with the impression, once again, that low-carb diets are bad for your heart. 

I’m not convinced.

Steve Parker, M.D.   

References:

Bradley, Una, et al.  Low-fat versus low-carbohydrate weight reduction diets.  Effects on weight loss, insulin resistance, and cardiovascular risk: A randomized control trial.  Diabetes, 58 (2009): 2,741-2,748.

Nainggolan, Lisa.  Low-carb diets hit the headlines again.  HeartWire, December 11, 2009.

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April 26, 2009 · 7:08 PM

Lipid Overload as the Cause of Type 2 Diabetes

An up-and-coming theory to explain type 2 diabetes suggests that abnormal lipid metabolism, not glucose/sugar metabolism, is the primary metabolic defect.  Roger H. Unger, M.D., writes about this in the March 12, 2008, issue of the Journal of the American Medical Association.

Early in the writing of this blog entry, I realized it is much too technical for many readers.  I’m writing this to solidify my own understanding of a new theory.  If you are not interested in physiology, you can quit reading now. 

Still with me? 

Definitions and Physiology

Diabetes is defined by high blood glucose (sugar) levels. 

The lipid family includes triglycerides (fats and oils), sterols (e.g., cholesterol), and phospholipids (e.g., lecithin, a major cell membrane component).  Fats are almost entirely composed of trigylcerides.  When fats are broken down, fatty acids are produced.  On the other hand, fatty acids can be joined together, along with glycerol, to form triglycerides. 

Glycogen is a storage form of glucose in liver and muscle tissue. 

Insulin is a protein hormone produced by pancreatic beta cells.  Insulin:

  1. lowers blood glucose levels by driving glucose into cells 
  2.  inhibits breakdown of glycogen into glucose
  3. inhibits formation of new glucose molecules by the body
  4. stimulates glycogen formation
  5. promotes storage of triglycerides in fat cells (i.e., lipogenesis, fat accumulation)
  6. promotes formation of fatty acids (triglyceride building blocks) by the liver
  7. inhibits breakdown of stored triglycerides
  8. supports protein synthesis. 

Fatty acids in muscle tissue block the uptake of glucose from the bloodstream by muscle cells.  Fatty acids in liver tissue impair the ability of insulin to suppress breakdown of glycogen into glucose, and impair the ability of insulin to suppress production of new glucose molecules.  In other words, an “excessive fatty acid” environment in liver and muscle tissue promotes elevated glucose levels.

Got that?  [This is very difficult material.]  Now on to . . .

 The Lipocentric Theory of Type 2 Diabetes

Type 2 diabetes may be caused by:

  1. Eating too many calories, leading to…
  2. High insulin levels, leading to…
  3. Stimulation of fat production, leading to…
  4. Increased body fat, leading to…
  5. Deposition of lipids in cells where they don’t belong (that is, not in fat cells), leading to…
  6. Resistance to insulin’s effects on glucose metabolism, leading to…
  7. Lipid accumulation in pancreatic beta cells, damaging them, leading to…
  8. Elevated blood glucose levels, i.e., diabetes.

Perhaps the key to understanding this is to know that “insulin resistance” refers to insulin having less ability to suppress glucose production by the liver, or less ability of various tissues to soak up circulating glucose.  Insulin resistance thereby leads to elevated glucose levels.  But insulin’s effect of “producing fats” (lipogenesis) continues unabated.  Excessive fats, actually fatty acids, accumulate not only in fat cells, but also in liver cells, muscle cells, pancreatic beta cells, and others.  This lipid overload can damage those cells.

If This Theory Is Correct, So What?

Steps #1 and 2 of the lipocentric theory involve excessive caloric intake and high circulating insulin levels, leading to problems down the road.  So overweight people should restrict calories and try to lose at least a modest amount of weight.  Particularly if already having type 2 diabetes or prone to it.

And what about people with type 2 diabetes who have insulin resistance and have poorly controlled glucose levels?  Most of these have high insulin levels already, contributing to a fat-producing state.  Adding more insulin, by injection, would not seem to make much sense.  The extra insulin would bring glucose levels down, but might also cause lipid overload with associated cellular damage.  Effective clinical strategies according to Dr. Unger would include 1) caloric restriction, which helps reduce weight, high insulin levels, and fat production, and 2) if #1 fails, add anti-diabetic drugs that reduce caloric intake (exenatide?), that reduce lipid overload (which drug?), or that do both.  Dr. Unger suggests consideration of bariatric surgery, for caloric restriction and cure of diabetes.

Compared with dietary fats and proteins, carbohydrates generally cause higher circulating insulin levels.  And type 2 diabetics taking insulin shots need higher doses for higher intakes of carbohydrate. So it makes sense to me to consider preferential reduction of carbohydrate intake if someone is going to reduce caloric intake.

Dr. Unger and I agree that reduction of excessive food intake and excess body fat is critically important for overweight people with type 2 diabetes.

Steve Parker, M.D.

References: Unger, Roger H.  Reinventing Type 2 Diabetes: Pathogenesis, Treatment, and Prevention.  Journal of the American Medical Association, 299 (2008): 1185-1187.

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