A New Tactic for Diabetes?

Summarized by Robert W. Griffith, MD
October 17, 2005

Introduction

Now the support for the Atkins low-carb approach is fading, people are renewing their interest in the benefits of carbohydrate and protein intake. In type 2 diabetics, combined intake of carbohydrate and protein stimulates plasma insulin release; and intravenous amino acids (the building blocks of proteins) have a similar same effect. Dutch scientists have now looked at insulin responses and plasma glucose levels in patients with type 2 diabetes after consumption of carbohydrate together with a protein hydrolysate (that's a mixture of protein and its constituent amino acids) and amino acid mixture. Their findings are reported in theAmerican Journal of Clinical Nutrition, and are summarized here.

What was done

Previous work by the same scientists, using animals and healthy volunteers, led to development of a mixture containing a protein (casein) hydrolysate together with two amino acids - leucine and phenylalanine. Ten long-term diabetic patients and ten matched healthy controls received this mixture together with a carbohydrate drink (glucose and maltodextrin), or the carbohydrate drink alone. They were assigned at random to one or the other; two weeks later they repeated the study, taking the alternate 'treatment'. This is what is known as a cross-over study. A glucose tolerance test was done before the first treatment, to determine the fasting glucose and insulin level and the glucose level 2 hours after a glucose drink. This allowed the insulin resistance to be calculated (1). Just before each treatment an infusion of radioactive-labeled glucose was started and run for 3 hours. Then the treatment (carbohydrate plus protein/amino acid mixture, or carbohydrate alone) was given by mouth. Immediately after each treatment repeated blood samples were taken for 3 hours to estimate the insulin response to the glucose intake.

What was found?

The men in each group - controls and diabetics - were of similar age (58 to 61) and size (BMI 27 to 27.5). At baseline, the controls had fasting glucose levels of 95.5 mg/mL (5.31 mmol/L) and 2-hr glucose levels of 90 mg/mL (4.98 mmol/L), whereas the diabetics had values of 193 mg/mL (10.71 mmol/L) and 360 mg/mL (20.01 mmol/L), respectively. The fasting plasma insulin, HbA1c, and insulin resistance index were all increased in the diabetics, compare with the healthy volunteers. Blood insulin levels increased in both treatment groups after the subjects had taken the treatments. However, there was a significantly greater response with the carbohydrate-plus-protein/amino acids than with carbohydrate alone: about a 300% increase vs. a 130% increase. Plasma glucose levels in the diabetics with the carbohydrate-plus-protein/amino acid group increased significantly during the first 90 minutes and then declined somewhat; with carbohydrate alone there was a similar increase, but no significant decline at 3 hours. The plasma glucose response was 28% lower in the carbohydrate-plus-protein/amino acid diabetics than in the carbohydrate-alone diabetics. (It was 33% lower in the control subjects, but this was attributed to greater distribution of glucose in the diabetic patients given the mixture.)

What these results mean?

The experimental design and the results obtained appear complicated, but the interpretation is clear. Diabetics taking carbohydrate with a mixture containing protein hydrolysate, leucine, and phenylalanine increased their insulin secretion, glucose disposal, and lowered plasma glucose levels after a meal. As the authors of the study suggest, nutritional interventions that have this effect "can be practical and effective tools in the treatment of diabetes". Long-term type 2 diabetics have reduced sensitivity of the beta cells of the pancreas to glucose. However, the insulin response in these diabetics to the carbohydrate-plus-protein/amino acids was found to be similar to that of non-diabetics given the carbohydrate alone, suggesting a 'normalization' of beta cell sensitivity. In fact, of course, good nutrition for diabetics contains a balance of carbohydrate and protein. What is new here is the addition of amino acids - leucine, phenylalanine, and, in other studies, arginine - along with a 'soup' of broken-down casein. It will require extensive clinical trials to realize the practicality of this approach towards managing type 2 diabetes; however, the concept clearly deserves to be explored to find a realistic solution.

Second, how could eating more dairy products affect cancer occurrence? It's been speculated that there's an increase in hormone intake affecting the ovarian tissue. Alternatively, lactose breaks down into galactose and glucose, and galactose may have a specific toxic effect on certain ovarian cells.

The fact that one cell type of ovarian cancer (those with serous cells) showed an association with lactose intake receives support from another study that shows a protective effect of physical activity on this type of ovarian cancer.1 Future research should concentrate, therefore, on determining the specific type of ovarian cancer that's open to influence by lifestyle changes. In the meantime, the nutritional benefits of milk - if it's not full-cream milk - should not be disregarded. As with all things, take dairy products in moderation. Don't forget that calcium, which is found in milk, may reduce the risk for a much more common cancer - colorectal cancer (see the last link below).

Footnotes

1. The insulin resistance index is the product of the fasting glucose level (in mmol/L) and insulin (in mU/L), divided by 22.5.

Source

• Co-ingestion of a protein hydrolysate and amino acid mixture with carbohydrate improves plasma glucose disposal in patients with type 2 diabetes. RJF. Manders, AJM. Wagenmakers , R. Koopman ,  et al., Am J Clin Nutr, 2005, pp. 76--83

Related Links
When Diet Is not Enough for a Type 2 Diabetic
Nutrition in Type 2 Diabetes

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