Diabetes in Norway
- 300 children develop type 1 diabetes every year.
- 1 in 20 Norwegians have been diagnosed with diabetes (245,000 individuals). Of these, estimates show that 28,000 have type 1 diabetes and 216,000 have type 2 diabetes.
- In addition, many may be unaware that they have diabetes.
- Among 80-year-olds, 1 in 9 have diabetes.
- Drug statistics suggest that the number of new cases of type 2 diabetes are no longer increasing.
- Type 2 diabetes can be prevented with increased physical activity and weight reduction.
- Individuals from South Asia and Africa have a higher risk of type 2 diabetes than other ethnic groups in the population.
- Diabetes is associated with serious complications and contributes significantly to the disease burden in Norway and worldwide.
What is diabetes?
Type 1 diabetes is caused by insulin deficiency and is treated with insulin injections. Type 2 diabetes is caused by a combination of impaired insulin secretion and insulin resistance (lack of insulin function). Type 2 diabetes is treated with diet and exercise, blood glucose-lowering tablets, sometimes with the addition of insulin injections.
Type 2 diabetes is much more common than type 1 diabetes, although type 1 diabetes is the most common form among children.
Number of diabetics in Norway
Diabetes is one of the most common chronic diseases in Norway yet we do not how many people have diagnosed or undiagnosed diabetes. By combining data from the Norwegian Prescription Database, the Health Studies in Nord-Trøndelag, Tromsø and some other studies, we can still obtain a reasonable estimate of the diabetes morbidity in Norway.
Number with type 1 and type 2 diabetes
Based on calculations, we can estimate that approximately 245,000 people (4.7 per cent), or 1 in 20 people are known to have diabetes. Of these, approximately 28,000 have type 1 diabetes and 216,000 have type 2 diabetes.
Figure 1. Estimated number of known cases of diabetes in the population. Unknown cases were not included. Source: Norwegian Institute of Public Health.
The figures in the figure above are based on the following calculation:
- 28,000 have type 1 diabetes. Calculations from the Norwegian Prescription Database estimate that 28,000 people (0.6 per cent of the population) had type 1 diabetes in 2013 (Strøm, 2014).
- Data from the Norwegian Prescription Database show that 183,000 people (3.5 per cent of the population) used blood glucose-lowering drugs in 2016. Most of these have type 1 or type 2 diabetes. Excluding those with type 1 diabetes, this means that nearly 3 per cent of the population (156,000) have type 2 diabetes that is treated with blood glucose-lowering drugs. These drugs are also used to treat gestational diabetes, polycystic ovary syndrome and obesity although we do not know how many are treated. The numbers are therefore approximate.
- 60,000 people are treated for type 2 diabetes with diet and exercise. Figures from representative general practitioners in 2005 showed that 28 per cent of patients with type 2 diabetes were treated with diet and / or exercise and 72 per cent with drugs (Cooper, 2009). Assuming this, we can estimate that the approximate 156,000 individuals estimated above represent these 72 per cent. 100 per cent would then equate to 216,000 (4 per cent of the population) who have been diagnosed with type 2 diabetes. Of these, just over 60,000 people (28 per cent) are treated with diet and / or exercise only. The estimate of 28 per cent may have changed since 2005 and must be interpreted with caution.
- Total: The conclusion is that approximately 244,000 people - rounded up to 245,000 – have diagnosed diabetes, type 1 or type 2. This accounts for 4.7 per cent of the population.
Unknown cases of type 2 diabetes: International studies and unpublished data from Norway suggest that many people are living with undiagnosed diabetes. Methodological problems make estimation difficult so we have chosen not to state any figures here (Hutchinson et al, 2012; Smith, 2007; Stene et al, 2004).
Trends over time
More and more people are living with diabetes
Data from the Prescription Database show that the number of people using blood glucose-lowering drugs has increased each year from approximately 110,000 people (2.5 per cent of the population) in 2004 to around 183,000 people (3.5 per cent of the population) in 2016, see Figure 3.
The increase may be due to more new cases per year (incidence), that more previously undiagnosed people with diabetes are being diagnosed or that those who have a diabetes diagnosis live longer. Figure 2 shows the factors that may affect prevalence.
Figure 2: Influencing factors for development of type 2 diabetes. Illustration: Norwegian Institute of Public Health, adapted from Ma & Tong, 2010.
New diagnoses may have levelled off
Every year, approximately 15,000-16,000 new patients begin to take drugs to lower their blood glucose levels. The figures have not increased in the period 2006-2011 (Strøm et al, 2014). This suggests that the number of newly diagnosed type 2 diabetes cases per year is no longer increasing.
There are no other national figures about time trends in diabetes incidence, with the exception of type 1 diabetes in children. Every year, approximately 300 new children develop type 1 diabetes in Norway. This figure has been stable since 2004 (Skrivarhaug et al, 2014).
Figure 3: Number of users of drugs to lower blood glucose levels 2004-2016. Source: Norwegian Prescription Database
Differences between population groups
Gender and age
Gender: In total, more men than women have diabetes, on average there are eight women per ten men with diabetes in Norway (Strøm, 2014). There is some variation in gender differences with age and ethnic group, see section on immigrants below.
Age: Both prevalence and incidence of type 2 diabetes increase sharply with age, to a peak at about 80 years of age. In 2012, almost 11 per cent of 80-year-olds used blood glucose-lowering drugs (Strøm, 2014).
Most studies, both from Norway and other countries, show that type 2 diabetes is more common in groups with lower education than in higher education groups (Agardh, 2011; Joseph, 2010).
Users of diabetes drugs: The proportion using blood glucose-lowering drugs appears to be highest in Østfold, Hedmark, Buskerud and Nord-Trøndelag, while the counties with the lowest proportion are Sogn og Fjordane, Rogaland and Akershus. This is shown by age-standardised statistics from the Prescription Database. See pages 21-22 of the Drug Consumption Report in Norway 2012 - 2016 (Drug Consumption in Norway 2012 - 2016 (report 2017:2)). There may be several possible explanations of county differences, so they should be interpreted with caution.
Type 1 diabetes: Finnmark and the northernmost counties have for many years had a lower incidence among children, while Vest-Agder and Aust-Agder have had relatively high incidence.
Diabetes in the Sami population
Data from SAMINOR 1 and unpublished data from SAMINOR 2 show little or no difference between Sami and non-Sami in the presence of diabetes (Broderstad, 2016; Naseribafrouei, 2016; Nystad, 2010).
Some immigrant groups are particularly vulnerable
Immigrants with origins from South Asia and some African countries have a higher risk of type 2 diabetes (Rabanal, 2013) and often develop type 2 diabetes at a younger age than ethnic Norwegians. A study in the Romsås and Furuset districts in Oslo showed that in the 30-59 year age group, 14 per cent of men and 28 per cent of women from Pakistan, India and Sri Lanka had previously or newly diagnosed diabetes respectively, compared with six and three per cent of ethnic Norwegians (Jenum, 2005).
There is probably a lower incidence of type 1 diabetes among immigrants from India and Pakistan (and some other countries in Asia and South America), at least among children (Dzidzonu, 2016).
There are estimated to be 415 million diabetics worldwide. In total, 12 per cent of global healthcare costs are used to treat diabetes (International Diabetes Federation, 2015) so diabetes is a major global disease burden.
Diabetes incidence is highest in some Arab countries, Turkey, Mexico and islands in the Pacific Ocean, see Figure 4. Compared to other countries, Norway has a relatively low incidence of diagnosed diabetes. The same applies to the other Scandinavian countries. In the case of type 1 diabetes alone, Norway, Finland and Sweden are among the countries in the world that top the statistics for new annual cases in children (DIAMOND Project Group, 2006).
Figure 4. The figure shows that diabetes prevalence is highest in some Arab countries, Turkey, Mexico and islands in the Pacific Ocean. Figures for 2015, age group 20-79 years, per cent. Age-adjusted prevalence. Source: Diabetes Atlas.
Genes and lifestyle affect risk
Genetics: Both type 1 and type 2 diabetes are caused by hereditary factors to some degree but these alone are rarely enough to develop diabetes. Rare genetic forms are the exception.
Other risk factors: At present, we know very little about modifiable risk factors for type 1 diabetes.
The most significant modifiable risk factors for type 2 diabetes are:
- overweight and obesity
- physical inactivity
- previous gestational diabetes
The health studies in Nord-Trøndelag show that people with body mass index (BMI) around 30 had more than 20 times higher risk of developing type 2 diabetes over an 11 year period compared with those of "normal weight" with body mass index of approximately 22 kg / m2 (Midthjell, 2001). For a person who is 175 cm tall, a weight of approximately 92 kg will give a BMI of 30, while a weight of approximately 67 kg gives a BMI of 22 kg / m2.
A large waist circumference ("abdominal obesity") is associated with a particularly high risk of type 2 diabetes.
Two sources highlight the incidence of gestational diabetes in Norway:
- National figures from the Medical Birth Registry show that the incidence of diagnosed gestational diabetes was approximately 4.5 per cent in 2015.
- In a study where sample of all pregnant women from Groruddalen in Oslo were tested, more than 10 per cent of them had gestational diabetes (Jenum, 2012).
In Groruddalen, there are many immigrants from South Asia, who are at higher risk of type 2 diabetes than ethnic Norwegian women. However, among ethnic Norwegians, about 10 per cent in this study had gestational diabetes. The difference between the study from Groruddalen and the Medical Birth Registry may be due both to differences in the composition of the population and that not all pregnant women in Norway are systematically tested for gestational diabetes. Many unknown cases are not registered in the Medical Birth Registry.
Women with gestational diabetes have a significantly increased risk of developing type 2 diabetes at a later stage. The risk factors for developing gestational diabetes are largely the same as for type 2 diabetes, including ethnicity and age. The criteria for gestational diabetes are under review.
Consequences of diabetes
People with type 1 and type 2 diabetes have increased mortality and risk of complications in the cardiovascular system, kidneys, eyes and nerves. Gestational diabetes is linked with an increased risk of complications during pregnancy for mother and child.
Estimates show that diabetes constitutes a significant part of the disease burden in Norway. For diabetes, years of life lost made up about 25 per cent of the number of disability adjusted years of life, while morbidity accounted for the remaining disease burden in 2015. Diabetes ranks as number seven in terms of morbidity, after for instance neck- and back pain, common mental disorders and migraines (NIPH, 2017).
Type 1 diabetes is not yet preventable. If the number of new annual cases of diabetes is to be reduced, interventions must be aimed at the most important risk factors for type 2 diabetes.
Intervention studies from Finland, USA and China have shown that improved diet, exercise and weight reduction reduce the number of new cases of type 2 diabetes within high risk groups. However, it is a challenge to identify the most effective interventions that trigger individual lifestyle changes and are feasible for the general population.
As part of the Exercise in Romsås study, a number of local interventions were introduced, including well-lit footpaths, organised training groups and information posters. These interventions resulted in increased fitness and reduced weight gain among participants three years later (Jenum et al, 2006). The study concluded that it is possible to reduce weight gain with interventions aimed at the general public but co-ordinated and targeted efforts from all relevant stakeholders are necessary.
Close monitoring and routine registration of data are needed to evaluate and document any effects of interventions to reduce the morbidity of diabetes. The current data in Norway are inadequate for this purpose.