Risk factors in type 2 diabetes with emphasis on blood pressure, physical activity and serum vitamin D

Abstract

Background Type 2 diabetes is a common chronic disease with a two-fold increased risk for cardiovascular morbidity and mortality and has an increasing prevalence worldwide. This thesis is based on a study conducted in primary health care in Östergötland and Jönköping, Sweden. The aim of the thesis was to evaluate new risk markers to identify patients with high risk of developing cardiovascular disease in middle-aged men and women with type 2 diabetes. Methods Data from the cohort study CArdiovascular Risk in type 2 DIabetes – a Prospective study in Primary care (CARDIPP) was used. In paper III data were also used from CARDIPP-Revisited where all participants in the CARDIPP study were invited four years after the baseline investigation for a re-investigation. In paper IV data were used from CAREFUL which is a control group of 185 subjects without diabetes. The investigation included a standard medical history including data on diabetes duration and on-going medication. Anthropometric data were recorded and both office and ambulatory blood pressure were measured. The patients filled out a detailed questionnaire and physical activity was measured by using waist-mounted pedometers. Pedometer-determined physical activity was classified in four groups: Group 1: <5000 steps/day (‘sedentary’); Group 2: 5000-7499 steps/day (‘low active’); Group 3: 7500-9999 steps/day (‘somewhat active’); Group 4: and ≥10 000 steps/day (‘active’). Blood samples were drawn for routine analyses and also frozen for later analyses. The investigations at the departments of physiology included echocardiography, measurements of the carotid intima-media thickness, applanation tonometry and measurements of sagittal abdominal diameter. Results Paper 1: Patients with a non-dipping systolic blood pressure pattern showed higher left ventricular mass index and pulse wave velocity (PWV) compared with patients with ≥10% decline in nocturnal systolic blood pressure. Patients with <10% decline in nocturnal systolic blood pressure had higher BMI and sagittal abdominal diameter, lower GFR and higher albumin:creatinine ratio and also higher levels of NT-proBNP than patients with a dipping pattern of the nocturnal blood pressure. Paper 2: The number of steps/day were inversely significantly associated with BMI, waist circumference and sagittal abdominal diameter, levels of CRP, levels of interleukin-6 and PWV. Paper 3: At the 4-year follow-up the change in PWV (ΔPWV) from baseline was calculated. The group with the lowest steps/day had a significantly higher increase in ΔPWV compared with the group with the highest steps/day. The associations between baseline steps/day and ΔPWV remained after further adjustment in a multivariate linear regression statistically significant (p=0.005). 23% of the variation in the study could be explained by our model. Every 1000 extra steps at baseline reduced the change in ΔPWV by 0.103 m/s between baseline and follow-up. Paper 4: Low vitamin D levels were associated with significantly increased risk for premature mortalit...