Transcript Document

Risk factors for complications of type 1 diabetes: A
nationwide comparison
Including a comparison with the general population
Eleanor J Hothersall1 on behalf of the Scottish Diabetes
Research Network Epidemiology Group*
1 University
Background
Type 1 diabetes (T1DM) is associated with an elevation in the
risk of cardiovascular disease (CVD) and all-cause mortality1,
with higher relative risks of cardiac events in women than
men with diabetes2. Explanations for this are unclear, but one
hypothesis is that rates of risk factors are higher in women
than men. Few studies exist comparing rates of risk factors in
T1DM with the general population3,4.
We compared risk factor prevalence (smoking, obesity,
hypertension, raised cholesterol and poor glycaemic control)
and attainment of risk factor target levels5 in the T1DM
population with published data from the Scottish Health
Survey6 (SHS), an annual representative survey of the general
population of Scotland.
Methods
The Scottish Care Information–Diabetes Collaboration (SCIDC) database was used to identify 21,290 people with T1DM
aged ≥16 years who were alive any time from 1st Jan 2005 to
31st May 2008 with available risk factor data. We extracted
risk factors (non-fasting lipids, blood pressure, current
smoking, body mass index) and medication history.
Comparable risk factor data was extracted from the SHS
(n=7,531).
Comparisons were made within age bands and by sex.
Prevalences and means in the T1DM population have been
standardised against the age/sex distribution of the general
population using the weighted denominators in the Scottish
Health Survey6.
Results
Rates for the general population and age-standardised rates
for the population with T1DM are shown by gender in Table 1.
Smoking
Crude estimates of smoking prevalence show higher rates of
smoking among men than women, and higher rates in men
with T1DM than men the general population (29.1% vs.
26.0%), but this is non-significant after age standardisation,
reduced to 27.5% (p=0.581). In contrast, women with T1DM
have a lower smoking prevalence than the generalpopulation
(23.9% vs. 25.0%), which is even lower after age
standardisation (22.3%, p<0.001).
Obesity
Obesity, as defined by a BMI≥30, varies when examined by age
group. Obesity rates are slightly higher in those with than
without T1DM< 55 years of age and are then lower thereafter.
Overall, obesity is less common in the men with T1DM than
women, and less common in the population with T1DM than
the general population; a relationship which is clearer with age
standardisation for men (22.4% vs. 26.9%, p<0.001), but nonsignificant in women (27.3% vs. 27.6%, p=0.889).
Blood pressure
Blood pressure control changes markedly across age ranges
(Figure 1). Hypertension is more frequent in T1DM than the
general population in every age group. In T1DM, but not in the
general population, significantly more men than women have
hypertension. Age standardised rates for hypertension show
that treatment rates of hypertension are higher in T1DM than
the general population (77.5% vs. 41.9% of those with BP
>140/90mmHg or on antihypertensive medication; 80.3% vs.
53.0% in women, p<0.001).
Successful treatment, defined by a blood pressure
<140/90mmHg, is nearly equal across the sexes in T1DM
(44.1% for men, 45.4% for women), which is not the case for
the general population (24.0% for men, 27.0% for women,
p<0.001 for both sexes).
Figure 1. Blood pressure control in T1DM and general population,
by age group
Cholesterol
Crude cholesterol levels are lower in T1DM than the general
population (30.5% men ≥5mmol/l vs. 53.6% in the general
population; 37.8% vs. 57.4% for women). Adjusted rates remain
significantly different, at 29.4% for men and 37.2% for women
(p<0.001 for both sexes). The difference between men and
women with T1DM is also significant, indicating lower
treatment rates in women.
of Dundee
Table 1. Risk factors in population age 16+ with T1DM (age standardised) and general population 6.
T1DM
(95% CI)
General population
Current smoker (%)
Men
27.0
27.5
(26.7, 28.3)
Women
22.3
25.0
(21.4, 23.1)
BMI ≥30 (%)
Men
26.0
22.4
(21.6, 23.1)
(95% CI)
(25,28.6)
(23.5, 26.5)*
(24.3, 27.7)*
Women
27.3
(26.4, 28.3)
27.5
(25.9, 29.20)
BP >140/90mmHg, or Men
on BP Drugs (%)
Women
(%) of these on
Men
treatment
Women
(%) BP controlled
Men
Women
Cholesterol ≥5mmol/l Men
(%) ( 16-64 years)
Women
HbA1c ≥6.5% (%)
Men
58.0
(57.1, 58.9)
34.6
(31.7, 37.5)*
55.2
77.5
(54.1, 56.2)
(77.8, 79.8)
30.4
41.9
(27.7, 33.1)*
(42.5, 52.9)*
80.3
44.1
45.4
29.4
(84.8, 84.8)
(42.6, 45.1)
(45.4, 45.4)
(28.5, 30.3)
53.0
24.0
27.0
53.6
(47.7, 58.3)*
(19.6, 28.4)*
(22.3, 31.7)*
(49.8, 57.4)*
37∙2
93.1
(36.1, 38.3)
(92.6, 93.6)
57.4
(53.7, 61.1)*
Women
94.0
* p<0.001 for difference between T1DM and general population
(93.6, 94.6)
Glycaemic control
Glycaemic control, measured by HbA1c is broadly similar across
age groups, as indicated by the fact that age standardisation
has little effect (93.5% crude rate, 93.1% age standardised in
men; 94.1% crude rate in women, 94.0% age standardised in
women, p<0.001 for both sexes).
imbalance seen in some risk factors also merits urgent
attention. In particular, the higher prevalence of smoking
and hypertension in men, and the lower treatment rates for
cholesterol in women. This latter may go some way to
explaining the increased CVD risk seen in women with
T1DM.
Conclusions
Nearly twenty years ago, the Diabetes Care and Complications
Trial (DCCT) demonstrated the preventability of many diabetic
complications with tight glycaemic control7 and longer term
follow up of the participants showed a reduction in CVD8.
Since then guidelines have emphasised tighter glycaemic
control, smoking cessation, blood pressure control, and above
40 years of age, statins are recommended for most
patients9,10. To an extent these guidelines are having an effect:
cholesterol levels are now substantially lower in type 1
diabetes patients than in the background population. This
reflects the targeted use of cholesterol-lowering medication in
this group. HbA1c levels however remain very high in those
with diabetes. Hypertension and prevailing blood pressures
remain higher despite more intensive intervention.
References
1. . Orchard TJ et al. (2006) Type 1 Diabetes and Coronary Artery Disease. Diabetes Care
29: 2528-2538.
2. Soedamah-Muthu SS, et al. (2006)High Risk of Cardiovascular Disease in Patients With
Type 1 Diabetes in the U.K.: A cohort study using the General Practice Research Database
Diabetes Care 29 (4) p. 798-804.
3. Wannamethee S, et al. (2011) Do women exhibit greater differences in established and
novel risk factors between diabetes and non-diabetes than men? The British Regional
Heart Study and British Women's Heart Health Study. Diabetologia DOI 10.100.
4. Colhoun HM, et al. (1999) The scope for cardiovascular disease risk factor intervention
among people with diabetes mellitus in England: a population-based analysis from the
Health Surveys for England 1991-94 Diabetic Medicine 16 (1) p. 35-40.
5. Scottish Intercollegiate Guidelines Network (2010) SIGN 116: Management of
Diabetes. A national clinical guideline http://www.sign.ac.uk/pdf/sign116.pdf
Accessed:14th April 2012.
6. The Scottish Government (2009) The Scottish Health Survey 2008 Edinburgh, The
Scottish Government.
7. The Diabetes Control and Complications Trial Research Group (1993) The Effect of
Intensive Treatment of Diabetes on the Development and Progression of Long-Term
Complications in Insulin-Dependent Diabetes Mellitus. New England Journal of Medicine
329: 977-986.
8. Nathan DM, Cleary PA, Backlund J-YC, Genuth SM, Lachin JM, et al. (2005) Intensive
diabetes treatment and cardiovascular disease in patients with type 1 diabetes. New
England Journal of Medicine 353: 2643-2653.
9. American Diabetes Association (2011) Standards of Medical Care in Diabetes—2011.
Diabetes Care 34: S11-S61.
There remains substantial scope for much greater prevention
of diabetic complications including an assertive attempt at
preventing smoking uptake in those with T1DM. The gender
Acknowledgements
This work was supported by the Wellcome Trust through the Scottish Health Informatics Programme (SHIP) Grant (Ref WT086113). SHIP is a collaboration between the Universities of Aberdeen, Dundee, Edinburgh, Glasgow and St Andrews and the Information Services Division of NHS Scotland
*The Scottish Diabetes Research Network Epidemiology Group Members involved in this study were Helen M. Colhoun, Shona Livingstone, Eleanor Hothersall, Helen Looker, Sarah Wild, Robert Lindsay, John Chalmers, Stephen Cleland, Graham Leese, John McKnight, Andrew Morris, Donald Pearson, Norman Peden, John Petrie, Sam Phillip, Naveed Sattar and Frank
Sullivan. Poster produced with assistance from Shona Livingstone and Professor Helen Colhoun