Commission staff working document - Summary of main points of scientific basis of the dietary recommendation for diabetics
Date: 2008-07-10
Institutions: European Commission
Subjects: diabetes, dietary product, health legislation, health policy, nutrition, public health, report, therapeutics

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COMMISSION OF THE EUROPEAN COMMUNITIES 

Brussels, 10.7.2008 
SEC(2008) 2294 

COMMISSION STAFF WORKING DOCUMENT 

SUMMARY OF MAIN POINTS OF SCIENTIFIC BASIS OF THE DIETARY 
RECOMMENDATION FOR DIABETICS 

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SUMMARY OF MAIN POINTS OF SCIENTIFIC BASIS OF THE DIETARY 
RECOMMENDATION FOR DIABETICS 

This document's aim is to contribute to comprehension of document COM(2008)392 

In 2004 a group coordinated by Mannii on behalf of the Diabetes and Nutrition Study Group 
of  the  European  Association  for  the  Study  of  Diabetes  (DNSG  of  the  EASD)  reviewed  the 
evidence for nutritional approaches to the treatment and prevention of diabetes mellitus and 
made  recommendations  based  on  evidence  for  dietary  advice  to  people  with  diabetes.  The 
strength of evidence for each of the recommendations was graded according to the nature of 
the studies on which they were based. Below is a summary of some of the main points of the 
review. 

Energy balance and body weight 

The  review  concluded  that  those  who  are  overweight  (BMI  above  25  kg/m2  should  lose 
weight  so  that  the  BMI  moves  towards  the  recommended  range  of  between  18.5  and  25 
kg/m2. The prevention of weight gain and the maintenance of a desirable weight is important. 
While it may not always be possible for individuals to achieve or maintain a desirable BMI, 
modest  weight  loss  (under  10%  body  weight)  improves  insulin  sensitivity  and  glucose 
tolerance and reduces lipid levels and blood pressure. 

Dietary fats 

People  with  diabetes  mellitus  have  an  increased  risk  of  cardiovascular  disease,  which  is 
around  2-4  times  greater  than  for  people  without  diabetes.  The  evidence  supporting  the 
recommendations  for  dietary  fat  intake  is  mainly  based  on  studies  involving  non-diabetic 
subjects.  There  are  no  controlled  dietary  intervention  studies  of  sufficient  power  among 
people with diabetes. There are some studies on people with diabetes comparing the effects of 
diets with different fatty acid composition that support the evidence in respect of non-diabetic 
subjects. It is recommended that total fat intake should not exceed 35% of total energy due 
to  the  increased  body  weight  of  people  on  high-fat  diets.  In  addition,  high  fat  intakes  may 
have adverse effects on insulin sensitivity.  

The evidence in the case of non-diabetic subjects that exchange of saturated fatty acids with 
unsaturated  fatty  acids  or  carbohydrates  reduces  plasma  LDL  cholesterol  is  supported  by  a 
few  controlled  studies  on  subjects  with  diabetes.  In  contrast  to  other  saturated  fatty  acids, 
though,  stearic  acid  does  not  increase  cholesterol.  The  consumption  of  saturated  fatty  acids 
and trans fatty acids causes an increase in blood insulin levels. In two prospective studies on 
subjects  with  diabetes,  the  ratio  of  polyunsaturated  to  saturated  fatty  acids  in  the  diet  was 
significantly  associated  with  coronary  heart  disease  events.  The  recommendation  is  that 
saturated and trans fatty acids should provide less than 10% of total energy. 

Regarding monounsaturated fatty acids (MUFA), Mann notes controlled studies, mainly on 
subjects  with  diabetes  whose  weight  is  within  the  normal  range,  indicating  that  serum  lipid 
levels may be improved by the substitution of a certain amount of MUFA for carbohydrates. 
The effects were seen when the substituted carbohydrates were mainly starch-rich foods with 
a low content of dietary fibre and high glycaemic index. The dietary recommendation is that 
oils  rich  in  MUFA  are  useful  fat  sources  and,  depending  on  individual  preferences,  may 
provide 10-20% of total energy, provided the total fat content of the diet is less than 35% total 
energy. 

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The  replacement  of  saturated  fatty  acids  with  polyunsaturated  fatty  acids  has  positive 
effects  on  serum  lipid  levels,  lipoprotein  concentration  and  composition  and  insulin 
sensitivity. The effects of mono- and polyunsaturated fatty acids on blood glucose and blood 
lipid  levels  appear  similar.  A  high  polyunsaturated  to  saturated  fatty  acid  ratio  has  been 
associated  with  a  low  risk  of  fatal  cardiovascular  events  in  people  with  diabetes.  It  is 
recommended that polyunsaturated fatty acid intake should not exceed 10% of total energy. 

With  respect  to  n-3  polyunsaturated  fatty  acids  there  are  no  published  controlled  studies  to 
suggest  that  supplementation  with  n-3  fatty  acids  improves  insulin  sensitivity.  There  are 
insufficient data to make specific recommendations on the optimal ratio of n-3:n-6 fatty acids. 
However, in line with the recommendations for the general population, it is recommended that 
dietary intake of n-3 fatty acids be encouraged through consumption of fish and plant sources 
of n-3 fatty acids. 

On  the  basis  of  data  relating  to  non-diabetic  people  and  people  with  type  1  diabetes,  it  is 
recommended to restrict dietary intake of cholesterol, as increased plasma cholesterol levels 
are associated with increasing intake of cholesterol. The recommendation is that daily intake 
of cholesterol should not exceed 300mg. 

Carbohydrates 

The recommended range of carbohydrate intake of 45-60% of total is based on the limits for 
the intake of fats and protein. The review notes a meta-analysis comparing the effects of high-
carbohydrate diets with diets higher in MUFA and lower in carbohydrates. It concluded that 
the long-term effects on glycaemic control of the different diets were comparable. In some of 
the  high-carbohydrate  studies  there  were  untoward  effects  on  the  fasting  triglyceride  levels 
which  can  be  avoided  if  the  carbohydrate  foods  are  rich  in  dietary  fibre  and/or  have  a  low 
glycaemic  index.  The  review  notes  that  when  choosing  carbohydrate-containing  foods  their 
effect  on  insulin  sensitivity,  serum  lipids  and  energy  balance  should  be  considered  and  that 
people  with  diabetes  should  regularly  consume  vegetables,  legumes,  intact  fruits  and 
wholegrain cereals. 

The review notes that controlled studies have indicated that increased intake of dietary fibre 
is associated with improved blood glucose levels. Ideally the intake of dietary fibre should be 
40g/day or more, of which half should be soluble fibre. In addition, several but not all studies 
of  diets  rich  in  soluble  fibre  have  found  an  association  between  high-fibre  diets  and  lower 
levels of total and LDL cholesterol. The review recommends that people with diabetes should 
consume foods naturally rich in dietary fibre and that the daily intake should ideally be more 
than 40g. It suggests that daily consumption of at least five servings of fibre-rich vegetables 
or  fruit  and  at  least  four  servings  of  legumes  each  week  can  help  to  provide  the  minimum 
recommended  intake  of  fibre,  whilst  cereal-based  foods  should  wherever  possible  be 
wholegrain. 

The  glycaemic  index  (GI)  was  proposed  in  the  early  1980s  as  a  method  to  guide  food 
selection.  A  meta-analysis  of  controlled  dietary  intervention  studies  comparing  diets 
containing high GI and low GI foods noted an improvement in mean blood glucose control. 
The effect of the GI of foods on blood glucose is independent of the effects of other dietary 
interventions. The review makes certain caveats about the use of GI for the selection of foods 
but concludes that carbohydrate-rich, low GI foods are suitable as carbohydrate-rich choices 
provided other attributes of the foods are appropriate. 

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Regarding  sucrose,  the  review  notes  that  in  the  1980s  several  randomised  controlled  trails 
demonstrated  no  adverse  effects  on  glycaemic  control,  lipids  and  lipoproteins  when  diets 
containing small amounts of sucrose were compared with “sucrose-free” diets. There are no 
studies  available  to  make  specific  recommendations  for  the  maximum  intake  of  sucrose  or 
free sugars by people with diabetes. The recommendation of limiting intake to less than 10% 
of total energy is based on experts' recommendations for the general population. 

Protein 

The  review  makes  the  following  recommendations  in  relation  to  protein  based  on  the 
available evidence. In people with diabetes with no evidence of nephropathy, protein intake 
may  provide  10-20%  of  total  energy;  in  people  with  type  1  diabetes  with  established 
nephropathy,  protein  intake  should  be  at  the  lower  end  of  the  acceptable  range,  which  is 
around 0.8g/kg normal body weight per day. 

Antioxidant nutrients, vitamins, minerals and trace elements 

Evidence  in  relation  to  non-diabetic  people  suggests  that  a  range  of  antioxidant  nutrients, 
vitamins,  and  foods  rich  in  them  protect  against  cardiovascular  disease.  Short-term  studies 
involving  the  consumption  of  foods  rich  in  these  nutrients  and  supplementation  studies 
confirm that markers of oxidative stress can be favourably influenced by substantial intakes. 
However, studies with clinical endpoints, principally involving non-diabetic people, have not 
demonstrated  beneficial  effects.  The  group  recommended  people  with  diabetes  to  eat  foods 
rich in such nutrients but did not recommend supplements. 

Moderate  dietary  sodium  restriction  produces  a  substantial  reduction  in  systolic  blood 
pressure in mildly hypertensive people with type 2 diabetes. It is recommended that, as for the 
general population, people with diabetes should restrict their daily salt intake to under 6g. 

The  review  noted  that  there  is  evidence  that  some  people  with  diabetes  have  low  levels  of 
circulating magnesium and that magnesium depletion of muscle and bone has been observed 
and linked to retinopathy and polyneuropathy. In addition, it has been suggested that there is a 
role for magnesium supplementation in halting the progression of these conditions. However, 
the group concluded that confirmation of the observations would need to be available before 
firm recommendations could be made. 

The review notes that low levels of zinc and chromium and high levels of copper have been 
reported  in  people  with  diabetes  but  concluded  that  there  was  no  evidence  to  suggest  that 
these observations should influence nutritional dietary recommendations. 

Alcohol 

Moderate amounts of alcohol may be associated with improved insulin sensitivity and, in non-
diabetic subjects, is linked to reduced risk of cardiovascular disease. However, alcohol can be 
an  important  energy  source  and  can  also  be  associated  with  raised  levels  of  blood  pressure, 
increased triglycerides and an increased risk of hypoglycaemia. There are no conclusive data 
on  an  appropriate  upper  limit  of  alcohol  intake  for  people  with  diabetes,  so  the 
recommendation is based on what is suggested for the general population – a moderate intake 
(up to 10g/day for women and 20g/day for men). 

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The  above  summary  reflects  the  conclusions  included  in  the  review  by  Mann,  although  it 
should be noted that there is no evidence of arguments contradicting their main conclusions 
with  regard  to  dietary  advice.  The  technical  review  by  Franz  that  formed  the  basis  of  the 
American Diabetes Association position statementvi draws similar conclusions. 

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REFERENCES 

ii. 

vi. 

Mann,  J.I.  et  al.  Evidence-based  nutritional  approaches  to  the  treatment  and 
prevention of diabetes mellitus. Nutrition, Metabolism, and Cardiovascular Diseases 
(2004) 14: 373-394. 

American  Diabetes  Association.  Evidence-based  nutrition  principles  and 
recommendations  for  the  treatment  and  prevention  of  diabetes  and  related 
complications (Position statement). Diabetes Care, 2002, 25: S50-S60.  

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