Low carb diet could benefit obese diabetics, says study

It is well established that some type 2 diabetics can achieve dietary control of their condition without the need for medication. And this new Swedish study adds to this by suggesting that the one fashionable low-carb diet may be one such effective approach.

The new study, published in the open access journal Nutrition and Metabolism​ (Vol. 3, number 22), adds to earlier research by the same scientists that obese people with type 2 diabetes could improve body weight and blood sugar levels over a six-month period by sticking to the low carbohydrate diet.

And further follow-up shows that sticking to the diet for 22 months continued to provide benefits to the subjects, and "is an effective tool in the management in motivated obese patients with type 2 diabetes."​

Dr. Jorgen Nielsen and Dr. Eva Joensson from Blekingesjukhuset, Karlshamm in Sweden, recruited 31 obese type 2 diabetics (average weight at baseline 100.6 kg, BMI 36.1 kg per sq.m) and assigned 16 to the low carbohydrate diet (20 per cent carbs) and 15 continued to eat their normal diet (55 to 60 per cent carbs). Both diets were equal in calories (1800 kcal for men, 1600 kcal for women).

After 6 months, subjects eating the low carb diet reported an average weight loss of 11.4 kg and a reduction of BMI of 4.1 kg per sq.m. Subjects eating the normal diet reported weight loss of about 3.5 kg.

Additionally, when the researchers measured blood levels of hemoglobin A1c (HbA1c), the form of hemoglobin usually used to follow plasma glucose concentrations over time, they found that the low-carb diet led to improvements over six months, and these improvements continued for the two years of study.

HbA1c levels for the low-carb diet fell from the starting value of eight per cent to 6.6 per cent after six months, and stayed almost constant at 6.9 per cent after 22 months. For the normal diet, HbA1c levels fell by 0.9 per cent.

"Advice on a 20 per cent carbohydrate diet with some calorific restriction to obese patients with type 2 diabetes has lasting effect on bodyweight and glycaemic control,"​ said Nielsen and Joensson.

The weight reduction observed was attributed to the reduction in calories.

"Intentional weight loss in type 2 diabetes patients is association with a reduced mortality of 30 to 40 per cent. For the average patient each kilogram weight loss is associated with three to four months prolonged survival making it likely that the patients described here have achieved a survival benefit,"​ said Nielsen and Joensson.

However, Roopinder Braar, care advisor for British charity Diabetes UK, told NutraIngredients.com that, while the study confirmed the benefit of weight loss in obese people with diabetes on their diabetes control and general health, the charity would not recommend low carbohydrate diets for weight loss.

"Studies have shown that a healthy diet combined with physical activity is best for successful weight loss and is more effective than if you simply diet or exercise alone.​

"It is a common myth that you should cut out starchy foods like bread and potatoes to lose weight.​

"Reducing total carbohydrate to just 20 per cent of total daily energy means that a greater proportion of your calories will come from fat and protein and the diet may be low in fruit and vegetables. A diet high in fat and low in fruit and vegetables is linked to heart disease.​

"It is important anyone with diabetes who is trying to lose weight discuss it with your diabetes team who will advise them on how to lose weight safely,"​ said Braar.

An estimated 19m people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26m by 2030.

In the US, there are over 20m people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132bn, with $92bn being direct costs from medication, according to 2002 American Diabetes Association figures.