Our study confirms that there is a clear gap between measured blood pressure and blood lipid recommendations and the actual management in 45 to 74 years old T2D and non- T2D subjects in the general German population. More than 60% of participants with T2D did not reach the conservative blood pressure target of 140/90 mmHg and about 40% had prevalent dyslipidemia (total cholesterol/HDL-ratio of > =5). The analysis showed that about 70% of all T2D participants received anti-hypertensive medication, but 40% were insufficiently controlled. About 20% of the participants with T2D used lipid-lowering medication but 7% did not reach a total cholesterol/HDL-ratio of <5 despite medication intake. Approximately 80% of T2D subjects with currently elevated lipid levels were untreated. T2D patients had a worse cardiovascular profile compared to non-T2D subjects.
The choice of anti-hypertensive drugs differed between participants with and without diabetes, reflecting current recommendations . Many study participants used only one ATC group.
The odds of having blood pressure values > =140/90 mmHg decreased significantly over time. However, since the single studies differed in the frequency of hypertension and the individual study periods overlapped only in part, the effect was difficult to separate from the study effect and will be studied in more detail using longitudinal data.
We did not especially stress the differences between the individual studies, since they do not necessarily reflect regional differences in health care. The studies were not conducted simultaneously and data assessment and laboratory measurements were not standardized from the outset. The nationwide GNHIES98, SHIP and DHS had more unfavourable outcomes than the other studies which might be due to the fact that GNHIES98 and SHIP were the oldest studies and DHS had the smallest number of participants and only two blood pressure measurements.
Strengths and limitations
The essential strength of our study is the large population-based sample drawn from the general German population aged 45 to 74 years and the fact that both, laboratory measurements and information on medication intake were available.
Due to the pooling process only similarly collected and coded data of all six studies could be used and the least common denominator had to be found. Therefore, the definition of diabetes was based on self-report of physician’s diagnosis and treatment with anti-diabetic agents rather than on clinical diagnosis and medical records. Blood pressure was calculated using the mean of the second and third measurements in all studies except for DHS, where only two measurements were performed and used to calculate the mean. This might distort the frequency in DHS and contribute to the high proportion of participants with 64.2% having a blood pressure > = 140/90 mmHg compared to 49.3% in the other studies.
Moreover, measurements of blood pressure and lipids based on a single testing opportunity present evidence for the respective condition, but are not equal to a clinical diagnosis with repeated measurements. We cannot exclude cases of ‘white coat hypertension’, i.e. elevated blood pressure owing to the excitement of the unfamiliar situation.
Finally, all study participants were asked to bring packages of their medications to the study centres. However, due to non-compliance and forgetfulness it is possible that fewer packages were documented than had actually been prescribed. We might thus have underestimated medication intake, consequently overestimated the number of participants without treatment and probably underestimated the number of participants with insufficient treatment.
The results of our population-based study fortify the findings of patient-based German and international studies. Recently, Berthold et al.  described that approximately 60% of T2D patients from the German T2DSD-registry DUTY had uncontrolled systolic blood pressure > = 140 mmHg and about 50% had uncontrolled LDL cholesterol values > = 3.4 mmol/l. These proportions differed slightly with atherosclerotic disease location. The German ESTHER Study published in 2008 found that 78% of diabetes patients had hypertension diagnosed by a physician and only 12.8% of those who received anti-hypertensive pharmacotherapy achieved blood pressure levels below 130/85 mmHg. Physician diagnosed dyslipidemia was reported in 50% of all patients .
A nationwide French survey conducted in 2001 and involving 410 diabetologists found that the target blood pressure of < 140/80 mmHg was attained by 29% of patients and 58% had LDL values of < than 1.3 g/l. Control of blood pressure and LDL was not considered to be optimal .
Similarly, the authors of a Canadian study  concluded that T2D patients with cardiovascular co-morbidities are insufficiently treated with medication, perhaps because of the “glucocentric view” of diabetes. They focused on antiplatelet agents, statins and ACE inhibitors. Godley et al.  used insurance claims data of 977 hypertensive T2D patients in the US. Only 19.7% reached the stricter blood pressure goal of < 130/85 mmHg and 52% had dyslipidemia. A recently published US investigation by DeGuzman et al.  including 926 high risk patients with diabetes and concomitant atherosclerotic CVD found that although the vast majority of patients were prescribed recommended drug therapy and mean cholesterol and BP values were satisfactory, the percentage of patients actually treated to goals of current guidelines was moderate. About 40% had LDL values < = 70 mg/dl and about 60% reached a systolic BP of < = 130 mmHg.
Finally, data from 9,167 participants of the US NHANES (National Health and Nutrition Examination Survey) survey  showed that alongside an increasing prevalence of diabetes from 1999 to 2008 the frequency of self reported use of lipid lowering medication increased significantly. Accordingly, the proportion of participants reaching the LDL cholesterol goal of < 100 mg/dl also increased significantly from about 30% to about 50%. Although the use of antihypertensive preparations increased significantly from about 35% to about 60%, there was no change in the proportion of participants achieving the BP goal of < = 130/80 mmHg (about 50%). Moreover, only one in four people with diabetes attained both the LDL and BP targets simultaneously.
The scientific community engaged in health care management strongly postulates an aggressive treatment of dyslipidemia and hypertension and advocates the widespread use of drugs to effectively improve mortality and morbidity rates in patients at risk . A large number of blood pressure lowering preparations is available today. The choice of agents depends on individual intolerances and the therapeutic effect that varies among subjects. However, though general recommendations for T2D patients exist, there is large diversity in diabetes care programs  and uncertainty as to which medication classes are most suitable for patients with diabetes. Usually more than one preparation is needed to achieve the target value .
In general, ACE inhibitors should be used first, accompanied by diuretics depending on the presence of co-morbidities. Yet diuretics alone are suspected to negatively influence blood glucose . Beta blockers, AT1 blockers and calcium antagonists are recommended as well [2, 44]. Beta blockers are believed to mask hypoglycaemia in patients with T2D, though evidence suggests that that is not the case .
Further reductions of blood pressure target values seem not to be advisable though . Recently, the ACCORD study has given evidence that the reduction of systolic blood pressure to 120 mmHg did not reduce the primary endpoint (a composite of stroke, myocardial infarction and cardiovascular death) compared with the control group, in which a systolic blood pressure of 140 mmHg was targeted . Due to severe adverse reactions caused by anti-hypertensive medication the overall mortality rate was even higher. Moreover, some renal markers were alarmingly impaired. The number of stroke cases, though, could be lowered by 41%. The results of the ACCORD lipid substudy were similarly disappointing : Tight control of triglycerides and HDL cholesterol values was achieved with a combination of fenofibrates and statins. The endpoints were not significantly reduced.
Statins are usually prescribed to treat dyslipidemia. They are regarded as safe, provide significant cardiovascular benefits in different populations including the elderly and patients with diabetes, and may halt or slow atherosclerotic disease progression . Recently, concerns have been raised that statins may increase the risk of developing diabetes in postmenopausal women  and with intensive-dose treatment compared to moderate-dose treatment . However, the authors concluded that the mechanisms remain unclear and the putative risk needs to be balanced to well-known benefits.
Over and above, insufficient blood pressure and lipid control are not exclusively due to insufficient prescription of medication but to various factors related to the patient and the physician. Important aspects are insufficient awareness and motivation of the patient, reluctance to initiate lifestyle changes, poor compliance (e.g. because of forgetfulness, tolerability problems due to adverse side effects, polypharmacy and dosing schedule, co-payments) and failure to modify therapy, when it is indicated such as use of combination therapy if monotherapy proves to be inadequate [51, 52].
Thus, apart from medication and its design, to improve secondary prevention of cardiovascular disease in primary physician health care and especially in T2D patients, the following intervention programmes should be emphasized : education sessions for practitioners, medical management guidelines, physician profiling of prescribing patterns, and blood pressure monitoring kits for patients and patient education. A prominent example are T2D disease management programs (DMPs) implemented by the German social health insurance companies in 2003 which have already shown the improvement of healthcare processes and blood pressure control .
According to a small study by Asimakopoulou et al. , T2D patients are aware of their increased cardiovascular risk and even tend to overestimate it. However, in contrast to realistic informed concern that may motivate to choose a healthier lifestyle, immoderate anxiety and fear may lead to ignorance and repression including poor compliance with medical treatment.
Therefore, individual counselling and risk communication between a health professional and the patient is essential.