Prevalence of hypertension and obesity in patients with type 2 diabetes mellitus in observational studies: a systematic literature review

Abstract

Background: Hypertension and obesity are known to contribute, directly or indirectly, to the development of long-term complications of type 2 diabetes mellitus (T2DM). Knowing the prevalence of these comorbidities is important for determining the size of the population that may benefit from strategies that reduce blood pressure and weight while controlling blood glucose.

Methods: In this systematic literature review, electronic searches of PubMed, Embase, and the Cochrane Library were conducted to identify observational studies of hypertension and/or obesity prevalence in patients with T2DM throughout the world. The searches were limited to studies reported in English from January 1, 2001 to February 16, 2012.

Results: From a total of 2,688 studies, 92 observational studies provided prevalence rates for hypertension and/or obesity specifically in adults with T2DM. Fifteen studies of specific subtypes of hypertension or subpopulations with T2DM were subsequently excluded, leaving 78 studies (in 77 articles) for inclusion in this article. Of these, 61studies reported hypertension prevalence, 44 reported obesity prevalence, and 12 reported the prevalence of hypertension with obesity. Most studies had a low risk of bias regarding diagnosis of T2DM (70/78), hypertension (59/69), or obesity (45/47). The continental regions with the most observational studies of hypertension or obesity prevalence were Europe (n = 30) and Asia (n = 26). Hypertension rates typically were high in all regions; most studies presented rates above 50%, and many presented rates above 75%. Obesity rates exceeded 30% in 38 of 44 studies and 50% in 14 of 44 studies, especially those assessing central obesity (based on waist circumference). Among obese adults, hypertension rates were at or above 70% in Asia and above 80% in Europe; rates were lower in North and South America but still above 30%.

Conclusion: Around the world, hypertension and obesity, separately or together, are common comorbidities in adults with T2DM.

Keywords: T2DM; blood pressure; body mass index; epidemiology; waist circumference.

Figure 1

Flow diagram of review and inclusion/exclusion (Preferred Reporting Items for Systematic reviews and Meta-Analyses [PRISMA]). Notes: ^aData of interest = incidence or prevalence of hypertension and/or obesity among adults with T2DM (searches one and two) or risk association of hypertension/obesity with long-term micro- or macrovascular complications of T2DM (search one only); ^bdoes not exclude patients hospitalized with T2DM complications; ^cpublication types excluded were commentaries, case studies, interim reports when end-of-study data were available, and reviews for which primary data were already included; ^done article (Thomas and Atkins29) reported on two studies, for a total of 78 studies in 77 articles. Abbreviations: NHS EED, National Health Service Economic Evaluation Database; T2DM, type 2 diabetes mellitus.

Figure 2

Hypertension (HTN) prevalence rates among patients with type 2 diabetes mellitus. Notes: Superscript numbers correspond to reference numbers. For countries with more than one reference citation, the citations are provided in the following order: study presenting the low estimate; study presenting the high estimate; and, if applicable, study or studies presenting mid-range value(s). Mid-range values are not shown in the figure. ^aMean ages in the study by Hassing et al were 83.1–84.0 years; ^bSuh et al provided both low and high estimates; ^cThomas and Atkins provided both low and high estimates (two studies in one report); ^dthe low estimate in South America used an atypical definition of hypertension (the proportion of patients with systolic blood pressure >144 mmHg).

Figure 3

Prevalence of obesity defined by body mass index (BMI) among patients with type 2 diabetes mellitus. Notes: Superscript numbers correspond to reference numbers. For countries with more than one reference citation, the citations are provided in the following order: study presenting the low estimate; study presenting the high estimate; and, if applicable, study or studies presenting mid-range value(s). Mid-range values are not shown in the figure. ^aThomas and Atkins provided both low and high estimates (two studies in one report).

Figure 4

Prevalence of obesity defined by waist circumference (WC) among patients with type 2 diabetes mellitus. Notes: Superscript numbers correspond to reference numbers. For countries with more than one reference citation, the citations are provided in the following order: study presenting the low estimate; study presenting the high estimate. ^aKoehler et al provided both low and high estimates; ^bBosevski et al provided both low and high estimates.

Figure 5

Prevalence of hypertension among obese adults with type 2 diabetes mellitus. Abbreviations: AHD, antihypertensive drug; BP, blood pressure; DBP, diastolic blood pressure; SBP, systolic blood pressure.