Type 2 diabetes is a steadily increasing problem for healthcare systems worldwide and Germany is one of the most severely affected countries in Europe 1,2. As many patients live with undiagnosed diabetes, the high incidence and prevalence figures still underestimate the problem.
Early diagnosis and changes in lifestyle supplemented by individually tailored antidiabetic treatment can prevent or at least delay microvascular and macrovascular complications in manifest diabetes 3.
There is consensus that primary prevention is even more important to reduce the incidence, the associated disease burden and healthcare costs of this chronic progressive disease in the future 4. Theoretically, this should be relatively easy to achieve. As the most important risk factors for the development of diabetes have been well known for decades, almost all of them can be influenced or modified and thus support the decrease of the individual diabetes risk 5,6.
It is well known that physical inactivity and less favourable nutritional habits are the main drivers of weight gain and obesity concurrently promoting the development of impaired glucose tolerance, insulin resistance and finally type 2 diabetes mellitus. In Germany, more than half of the adult population is considered overweight and approximately one-quarter is already obese 7. Meanwhile, this disease is also increasingly being diagnosed in children and adolescents 8.
A family history of diabetes, hypertension and several other modifiable risk factors also contribute towards the development of impaired glucose metabolism and permanent hyperglycemia 9.
Background of the campaign
In 2005, the campaign ‘Knowing what Matters in diabetes: Healthier below 7’ was initiated to raise awareness of the disease, to identify individuals with a potential risk of developing diabetes and to inform those who are already affected about an optimized diabetes management; therefore, the term ‘below 7’ refers to the hemoglobin (Hb)A1c-target for those with a history of diabetes.
Everyone was invited to participate in the shopping mall activities – irrespective of known/unknown diabetes diagnosis, age, sex, BMI or other individual characteristics, and no selection process was applied. Thus, the participants of the campaign represent a random sample of the general population.
By the end of 2014, more than 31 000 individuals had participated voluntarily by completing standardized questionnaires and had undergone examinations with respect to key metabolic parameters and other diabetes risk factors. The results from 5098 participants who already had a manifest diagnosis of type 2 diabetes have been published earlier 1.
Methods applied during the campaign have been described in detail elsewhere 1. In brief, 45 single campaigns have been conducted in German shopping malls between 2005 and 2014 offering voluntary participation to visitors. This included the completion of a modified FINDRISK questionnaire with eight items 10 and additionally blood pressure (BP) and blood glucose measurement and optionally the determination of HbA1c.
In addition to the results published for participants with manifest type 2 diabetes 1, this paper presents the data collected from participants without a previous history of diabetes.
Weight and height were documented as indicated by participants. BP was measured in the right arm in the sitting position after an obligatory 5 minutes rest. Waist circumference was measured with an appropriate tape according to official recommendations 11. HbA1c was measured using the Progen/Alere A1c-test kit (Alere Technologies GmbH, Jena, Germany) as described previously 1. A modified version of Lindstroem’s FINDRISK questionnaire 10 was used.
After checking for completeness and plausibility, unlikely data were excluded from the statistical analysis. Missing data were not replaced. Because of missing items on history and type of diabetes in the 2005 questionnaire, this year was considered a feasibility period and therefore excluded from respective analyses.
As the investigation followed an exploratory approach, only descriptive statistical methods were used for data analysis. To detect trends during the 10-year observation period, the results of the campaign were examined year by year. The level of significance was generally set to 0.05, with α adjustment according to Bonferroni.
The biometric evaluation was performed using the ‘IBM SPSS Statistics 20’ statistical software (IBM Corporation, Armonk, New York, USA). Further details on statistics can be found in 1.
In total, from 45 single campaigns conducted in 25 German cities, 31 085 questionnaires were collected and consequently 26 522 complete questionnaires were evaluated (2006–2014). Of these 26 522 participants, the majority of 21 055 (79.4%) attendants reported no history nor a previous diagnosis of type 1 or type 2 diabetes mellitus. The proportion of participants without known diabetes varied between 73.4% (2011) and 88.0% (2013).
Age was documented in 21 035 participants without a previous history of diabetes. The majority (40%) of the individuals were older than 64 years of age, 21.7% were between 55 and 64 years of age and 38.4% were younger than 55 years of age.
In total, 62.5% of nondiabetic participants were women and 37.5% were men. This represented a significant difference between the sexes without any trend over time.
Diabetes in family history
Almost 40% of the participants without manifest diabetes reported manifest diabetes in first-degree and/or second-degree relatives.
The mean BMI was 26.1 kg/m2 and the median BMI was 25.6 kg/m2. About 16.5% of all nondiabetic participants, that is, one out of six individuals, were obese, nearly 40% were overweight and less than half of the individuals (43.7%) had a BMI in the normal range (Fig. 1).
Compared with the group of patients with diabetes, the BMI was lower in the nondiabetic group with a markedly lower rate of obesity (Table 1).
In all the participants, there was no trend towards an increase in BMI values over time (Fig. 2).
Waist circumference values were above the critical values (>102 cm in men and >88 cm in women) in 44.0% of the nondiabetic participants. No trend over time could be detected (Fig. 3).
More than a third (34.9%) of the participants without diabetes reported a lack of physical activity, meaning that they did not exercise regularly. However, in this group, there was a temporal trend towards more physical activity over the 10 years of the campaign (P<0.001; Fig. 4).
On average, 20% of nondiabetic participants reported less favourable nutritional habits, that is, no daily consumption of fruits, vegetables and whole-grain bread. A trend towards less favourable nutritional habits was found over the years (P<0.001; Fig. 5).
BP and concomitant antihypertensive therapy
The mean systolic BP in the nondiabetic group was 141.4 mmHg and the mean diastolic BP was 85.2 mmHg, with a trend towards slightly lower systolic (P<0.01) and higher diastolic (P<0.001) BP values over the 10 years (data not shown). Patients with diabetes had a significantly higher systolic BP (Table 2).
Antihypertensive treatment was more frequent in the patients with diabetes (Table 3); however, at least 35% of those without known diabetes reported previous and/or current use of antihypertensives. Thus, about one-third of the nondiabetic participants must have had hypertension as they took antihypertensive medication.
However, systolic BP above 140 mmHg was found in more than half of the individuals in the nondiabetic group (51%), whereas among patients with diabetes, this was even higher (67%) – despite more antihypertensive medication (Table 3).
Good BP control, as defined by less than 140/<90 mmHg, was found in 43% of the nondiabetic individuals and only 29% of the diabetic patients. As elevated BP is also one of the important predictors of type 2 diabetes, this furthers indicates the higher risk for DM2 in this nondiabetic population.
According to Lindström et al. 10, the FINDRISK sum score can take values between 0 (no risk at all) and 23 (considerable risk) (Table 4).
In total, about half of the nondiabetic participants had a low potential risk, 37% had a slightly increased risk, 14.3% showed a moderately increased risk and only 1.3% showed a very high risk of potentially developing type 2 diabetes within 10 years.
HbA1c (in a random subgroup)
A total of 4133 HbA1c, measurements were performed in individuals without previous diabetes, meaning that, randomly, about 20% of this group had their HbA1c measured during the campaign.
The median HbA1c value in the group of nondiabetics was 5.9% and thus significantly lower (P<0.001) compared with 6.9% in participants with manifest type 2 diabetes (n=4170). In contrast to patients with type 2 diabetes, no trend towards higher HbA1c values over time was observed in nondiabetics.
In this subgroup, with randomly measured HbA1c, surprisingly, a considerable proportion of individuals had an HbA1c of at least 6.5%, which is – according to ADA 12 – equivalent to the diagnosis of type 2 diabetes, and another 24% showed an HbA1c between 6.0 and 6.5%, which indicates a substantial risk (Table 5 and 12).
This study found a very high prevalence of risk factors for developing type 2 diabetes in a large group of nondiabetic participants of the campaign ‘Knowing what Matters in diabetes: Healthier below 7’ (Table 6). In the last 10 years, 21 055 individuals without a history of type 2 diabetes participated in a risk screening. In this group, a high proportion had a family history of diabetes, was overweight or obese and had an unhealthy lifestyle. Furthermore, hypertension was highly prevalent (and often uncontrolled); the FINDRISK questionnaire identified 16% with a substantial 10-year risk of diabetes and, even more surprisingly, in those in whom HbA1c was tested, we found that almost 20% of the individuals had an HbA1c of at least 6.5%, which means that a relevant proportion (1 out of 5) already had a diagnosed type 2 diabetes (Fig. 6).
Thus, in this nondiabetic group, we found a high proportion of participants with several risk factors for the development of diabetes (Table 6: almost 40% of the participants reported the presence of diabetes in first-degree or second-degree relatives, which was a lower percentage than in the group of patients with manifest type 2 diabetes mellitus (56%) 1. Overweight and obesity were highly prevalent, and yet not as high as in individuals with known diabetes. The waist circumference was above the critical values in 44% of the participants. An unhealthy lifestyle with a lack of physical activity was reported by 35% of the participants and less favourable nutritional habits were reported by 20%. Furthermore, hypertension was highly prevalent in the nondiabetic population, as indicated by the use of antihypertensives (35%) and the BP; 51% had a systolic BP more than 140 mmHg.
Furthermore, in the subgroup with HbA1c testing, not only did 18.5% already have manifest diabetes, another 24.2% had an HbA1c between 6.0 and 6.4%, indicating an increased risk of diabetes 12. Hence, these nondiabetic participants represent a high-risk group (Table 5).
Lifestyle modification needed
As BMI and body fat distribution are established risk factors for the development of type 2 diabetes, primary prevention has to target the main causes of overweight and obesity, mainly unfavourable nutritional habits and lack of physical activity. Therefore, it is alarming that among the participants without manifest diabetes, many more than half of them were overweight or obese and also nearly half of them had a waist circumference above the common threshold values that may indicate a metabolic disorder. As waist circumference is also directly associated with the amount of visceral fat, it is also closely linked to the pathophysiology of diabetes 13.
The risk of developing type 2 diabetes is further increased by a genetic disposition as about 40% of these individuals reported the prevalence of diabetes in close relatives.
As one out of three participants reported a lack of physical activity and one out of five participants had an unhealthy diet, lifestyle factors will contribute considerably towards the increasing incidence of diabetes in Germany within the next few years. Taking into account the reporting bias, the lifestyle-associated risk in the general population is certainly much higher than reported here.
BP control – a lot of room for improvement and a risk predictor for diabetes
The mean measured systolic BP in the nondiabetic group was 141 mmHg and the mean diastolic BP was 85 mmHg with a trend towards slightly lower systolic (P<0.01) and higher diastolic (P<0.001) BP values over the 10 years; 35% of the participants were on antihypertensives, but 51% of the individuals in the entire group had systolic BP above 140 mmHg and altogether a considerable proportion had uncontrolled hypertension (≥140/≥90 mmHg). Increased BP is not only a risk factor for cardiovascular disease but also another risk factor for the development of type 2 diabetes. Compared with individuals with diabetes, however, the prevalence of hypertension and uncontrolled BP was lower (Table 3).
Early detection and intervention matters
Numerous publications have clearly shown that prevention programmes aimed at a healthier diet and an increased physical activity can have a considerable beneficial effect on risk factors and diabetes incidence. Improvements in body weight, diet and exercise capacity can easily be achieved with modest efforts 14. However, more intensive lifestyle interventions and, in particular, a weight loss of at least 5% maintained over a longer period of time had a more pronounced effect in European clinical trials 15,16. Consequently, such improvements were associated with a markedly reduced incidence of diabetes over an observational period of one to several years 15–18, with lifestyle interventions being clearly superior to metformin and also improving associated cardiovascular risk factors such as hypertension and dyslipidaemia 17.
A recent systematic review evaluating 53 clinical studies with 66 intervention programmes in individuals at increased risk for type 2 diabetes confirmed that the recommendation of an increase in physical activity together with a healthier diet decreased body weight and fasting blood glucose levels, reduced the incidence of type 2 diabetes (relative risk reduction: 0.59) and improved other cardiometabolic risk factors 19. Risk factor control for diabetes prevention is even important in early adult life as a 30-year follow-up study in UK showed that higher BMI at 21 years of age is associated with an increased diabetes incidence during follow-up, although not to such an extent as in middle age 20.
Type 2 diabetes mellitus is a disease that is often not recognized until the presentation of severe complications such as stroke or myocardial infarction. 21.
As prediabetes and diabetes usually do not present with clearly noticeable symptoms – early detection requires other strategies to identify these individuals. Although an oral glucose tolerance test is still the method used to identify these patients, it is an invasive procedure, costly and time-consuming when used on a large scale. Thus, finding simpler, more pragmatic methods to identify individuals at high risk of progression to diabetes and who might benefit from targeted prevention is an important goal. One way is to use screening questionnaires such as FINDRISK or to screen for increased HbA1c. In this group, we found a considerable risk in 16% of the participants through the FINDRISK. As in the nondiabetic population, about 20% had their HbA1c measured (at random), surprisingly, more than 18.5% of the people who had it measured, showed a HbA1c above 6.5%, which indicates a very high rate of manifest, yet undiagnosed, diabetes 22,23.
This is in a somewhat higher range than other observations on the basis of HbA1c measurements in random samples showing undiagnosed type 2 diabetes in 7.3% in UK 12 and 9.4–9.7% in the USA 24, the latter figure being close to the age-adjusted prevalence of 8.2% in adults in the USA in 2010 25.
As described earlier 1, conclusions which can be drawn from the evaluation of the data from the ‘Knowing what Matters in diabetes: Healthier below 7’ campaign have some limitations including the nonrepresentative population, the restricted information collected with the modified FINDRISK questionnaire and the random subsample of HbA1c testing. Nonetheless, the results based on real-world data shed some more light on the condition of the general population in Germany who have not yet been affected by diabetes.
Information campaigns such as ‘Knowing what Matters in diabetes: Healthier below 7’ are an efficient way to reach individuals who are apparently healthy, but may have a potential risk of developing a clinically manifest diabetes in the near future.
Our findings in Germany confirm that the well-known risk factors for the development of diabetes, that is, overweight or obesity, unhealthy nutrition and decreased physical activity are very common and thus increase the risk for these apparently healthy individuals of developing type 2 diabetes within a couple of years. Surprisingly, a rather large proportion of those who had their HbA1c measured were diagnosed as diabetic with an HbA1c of at least 6.5%, indicating a high rate of undiagnosed individuals with diabetes and another 24% were at an increased risk for diabetes with an HbA1c (≥6.0 and <6.5%).
We know that prevention through even moderate lifestyle modification is effective; this is evidence based. Therefore, we need to focus more on early detection and early intervention. This all starts with providing information to the people. Campaigns such as this one, ‘Knowing what Matters in diabetes: Healthier below 7’, can help to address this issue as they help to increase disease awareness and prevention.
This not only applies to primary prevention, as in this subgroup, but also to secondary prevention in individuals already diagnosed with diabetes. In the long term, broad success can only be achieved by a sustained and consequent effort including all stakeholders.
Conflicts of interest
All authors were equally involved in the conception and design of the research and in the interpretation of the results. Stephan Jacob reports to have received honoraria from Abbott, Astra-Zeneca, Bayer, Berlin-Chemie, Bristol-Myers Squibb, Boehringer Ingelheim, Daiichi Sankyo Germany, Essex, Eumecom medical information training, GlaxoSmithKline, Janssen-Cilag, Johnson & Johnson, LighterLife UK, Lifescan, Lilly Germany, Merck, MSD Sharp & Dohme, Novo Nordisk, Novartis, Pfizer Germany, Roche, Sanofi-Aventis Germany, UCB, Solvay, Takeda and Viatris. Franz-Werner Dippel and Andrea Klimke-Huebner are employees of Sanofi-Aventis Germany. Werner Hopfenmueller has no conflicts of interest.
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Keywords:Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
diabetes mellitus; hypertension; primary prevention; risk factors; screening; type 2 diabetes