Eggs and Diabetes

The 2011-2012 Australian Health Survey reported 5.1% of adult Australians have diabetes and a further 3.1% are at high risk of developing diabetes1. The survey also found that for every 4 cases of diagnosed diabetes there was one case that goes undiagnosed.

For type 2 diabetes, the increased prevalence is likely driven by rising obesity, the ageing population, dietary changes, and sedentary lifestyles2. Body mass index (BMI), alcohol consumption and physical inactivity have been specifically identified as significant lifestyle risk factors impacting the development of type 2 diabetes in Australian adults3. Previously thought to only occur in adulthood, type 2 diabetes is now increasingly being identified in younger age groups.

EGG CONSUMPTION IN INDIVIDUALS WITH OR AT RISK OF DEVELOPING TYPE 2 DIABETES

It has been previously suggested that individuals with (or at risk of) type 2 diabetes may need to limit their intake of eggs (and/or dietary cholesterol intake) due to observational evidence of an association between higher egg intake ((>7 eggs/week (in most studies)) and an increased risk of cardiovascular disease (CVD)4-7. While some evidence indicates a link, two recent observational studies in US8 and UK9 adults found no evidence of an association between dietary cholesterol or higher egg intake and CVD in individuals with pre-diabetes or type 2 diabetes8,9. On the other hand, one recent longitudinal study in Korean adults indicated an increased risk of CVD amongst individuals with type 2 diabetes who consumed more than 4.2 eggs per week10. These mixed results are likely due to factors such as the inadequate control of confounders and, in some cases, small sample sizes. Authors have called for caution when interpreting these findings4.

Importantly, well-designed intervention studies do not indicate that higher egg intake has any adverse effects on CVD risk in individuals with or at risk of type 2 diabetes. A 2017 systematic review of six randomised controlled trials concluded that the consumption of 6 to 12 eggs per week, in the context of a diet that is consistent with guidelines on cardiovascular health promotion, has no adverse effect on major CVD risk factors in individuals at risk for developing diabetes or with type 2 diabetes11.

Furthermore, since the 2017 systematic review, the results of an Australian 12 month intervention study have been published which support the conclusion that eggs can be enjoyed by individuals with (or at risk of) type 2 diabetes. In the DIABEGG study, consuming ≥12 eggs per week produced no detrimental outcomes in CVD risk factors (including cholesterol, triglycerides, inflammatory markers, oxidative stress or measures of glycemia) for individuals with prediabetes or type 2 diabetes and overweight or obesity 12. These 12 month findings are an extension of the original 3-month DIABEGG study which showed that high egg (≥12 eggs per week) consumption vs low egg (<2 eggs per week) consumption, as part of a weight maintenance diet, had no detrimental effect on CVD risk factors13.

Overall, intervention studies in individuals with prediabetes, metabolic syndrome and type 2 diabetes indicate that eggs are an acceptable and convenient whole food option that can be consumed regularly as part of a healthy diet to manage these conditions.

BENEFITS OF EGG CONSUMPTION FOR INDIVIDUALS WITH OR AT RISK OF TYPE 2 DIABETES

Research in individuals with type 2 diabetes has also indicated that the inclusion of eggs daily may be beneficial as they may displace less healthful foods such as refined grains and boost levels of quality protein in the diet14.

As well as providing quality protein, eggs contain at least 11 vitamins and minerals, omega-3 fatty acids and antioxidants. Eggs can therefore make a valuable contribution to daily protein and nutrient requirements.

Further research has been carried out with the aim of determining if there is a relationship between egg consumption and risk of developing type 2 diabetes.

SUMMARY OF EPIDEMIOLOGICAL STUDIES INVOLVING EGG CONSUMPTION AND RISK OF DIABETES (T2DM)

A 2016 meta-analysis of twelve prospective cohort studies examined the risk of developing type 2 diabetes based on levels of egg consumption15 and found no overall association. In sub-analysis, egg consumption was positively associated with type 2 diabetes risk in US studies but no overall association was observed in non-US studies. This isolation to US populations suggests that egg consumption may be a marker of a broader dietary pattern in which the studies were conducted. For example in one of the US studies which found a significant association between egg consumption and type 2 diabetes 16 egg consumption was related to the Western dietary pattern characterised by a high intake of red or processed meat, French-fries, sweets and dessert, snacks and refined grains. Whereas, in the study conducted in Japan17 which found no association, egg consumption was strongly associated with prudent, traditional dietary patterns rather than a western dietary pattern.

Overall there is a lack of evidence relating egg consumption with incidence of type 2 diabetes. The current body of evidence highlights the importance of consuming eggs in the context of an overall healthy dietary pattern as recommended by the current Australian Dietary Guidelines18 as well as Diabetes Australia19 and the Heart Foundation20.

SUMMARY OF INTERVENTION STUDIES INVOLVING EGG CONSUMPTION AND INDIVIDUALS WITH/OR AT RISK OF TYPE 2 DIABETES

Clinical intervention trials have investigated the effect of egg consumption on glycaemic control in individuals with type 2 diabetes. This research includes the Australian DIABEGG study which found no difference in glycaemic control when individuals consumed 2 eggs per day or less than 2 eggs per week as part of a weight maintenance diet13 or weight loss diet and follow up period (12 months in total) 12. Furthermore a 2016 trial found no effect of the short term consumption of 2 eggs per day on glycaemic control in individuals with type 2 diabetes21. In the context of a 12 week weight loss diet, consumption of 2 eggs per day showed similar weight loss and improvements in glycaemic control as consuming 100g lean meat per day22. Another small study showed no significant differences on blood sugar levels or HbA1C when 1 egg per day for 5 weeks was consumed compared to an oatmeal and milk breakfast23. Overall clinical evidence to date shows a “lack of detrimental effects of eggs on lipoprotein or glucose metabolism” 24.

GESTATIONAL DIABETES

An analysis of two studies25 examined the effect of egg consumption before or during the first trimester of pregnancy on the risk of gestational diabetes. After adjusting for confounders, researchers in both studies found a 2.4-2.5 fold increased risk of developing gestational diabetes with the consumption of 10 or more eggs per week. However both studies found little to no effect on gestational diabetes risk for those who consumed less than seven eggs per week26. Including eggs in the diet of pregnant women can contribute a range of important nutrients to the diet. [For more information on the value of eggs in pregnancy see the Eggs and Pregnancy fact sheet]

CONCLUSIONS

Epidemiological evidence regarding egg consumption and its effect on people with diabetes is inconsistent and positive associations appear to be isolated to US based studies. Caution with interpretation is warranted particularly given evidence from clinical studies conducted to date do not support an association between egg consumption and risk of type 2 diabetes or CVD risk in individuals with (or at risk of) type 2 diabetes.

RECOMMENDATIONS

  • Further longer term studies would help further assess the effect of egg consumption in people with diabetes.
  • Overall dietary patterns, physical activity and genetics effect the development of type 2 diabetes more than a single food such as eggs27.
  • Prudent advice is that eggs may be included in the context of a diet low in saturated fat, containing known cardio-protective foods and meeting the guidelines for diabetes management. Eggs can contribute valuable nutrients including quality protein, vitamins and minerals in the diets of individuals with or at risk of type 2 diabetes.
  • Research supports the regular inclusion of eggs as part of a healthy diet. Furthermore, Diabetes Australia recommends individuals with diabetes follow the Australian Dietary Guidelines which support the consumption of eggs daily and conclude that “there do not appear to be any increased health risks associated with consumption of eggs”.18

This statement is for healthcare professionals only.

*One serve = 2x60g eggs (104g edible portion)

As diet-induced changes in plasma glucose levels, total cholesterol and lipoproteins vary considerably between individuals, the Egg Nutrition Council recommends individual discussion of the recommendations regarding egg intake with their health care professional.

USEFUL LINKS

Australian Dietary Guidelines: www.eatforhealth.gov.au/guidelines

Diabetes Australia: http://www.diabetesaustralia.com.au

American Diabetes Association: http://www.diabetes.org/

Joslin Diabetes Center: http://www.joslin.org/

References:

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  2. Shaw, J. & Tanamas, S. Diabetes: the silent pandemic and its impact on Australia.  (Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia, 2012).
  3. Li, J. & Kinfu, Y. Impact of socioeconomic and risk factors on cardiovascular disease and type II diabetes in Australia: comparison of results from longitudinal and cross-sectional designs. BMJ Open 6, e010215 (2016).
  4. Shin, J.Y., Xun, P., Nakamura, Y. & He, K. Egg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysis. Am J Clin Nutr 98, 146-159 (2013).
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