Anecdotally, I know that many of my colleagues in diabetes care worry about the attention we give to our patients with type 1 diabetes. Type 2 diabetes is at least 90% of the workload in relation to diabetes – there is enough clinical work to occupy us fully with prevention, aggressive risk-factor control and polypharmacy. The latter is particularly exciting, with new agents galore with high “standards of promotion” and an emerging evidence base.
There is good news for patients with type 1 diabetes. An Australian study (Huo et al, 2016) shows that life expectancy has improved by 1.5 years in women and 1.9 years in men, over a relatively short period (2003 to 2010). Hidden away somewhat in the paper is the fact that patients with type 1 diabetes still lose 12.2 years of life in comparison to the general population, however.
So, what can we do? Three of the papers summarised in this issue can give us a clear strategy to narrow this gap in life expectancy. From the DCCT/EDIC study (alongside) we learn that early good glycaemic control creates a metabolic legacy that reduces the risk of cardiovascular disease (CVD) over a 20-year period. The mechanism discussed is interesting and may be related to vascular stiffening, which is accelerated by poor glycaemic control by glycation of the vascular wall of arteries.
Severe hypoglycaemia must be avoided (see summary of Lu et al on page 93). Even a single episode of severe hypoglycaemia in the preceding year was associated with an odds ratio of 2.74 of all-cause mortality and 2.02 of CVD. The figures are similar if there have been episodes of hypoglycaemia in the preceding 1 to 3 years and 3 to 5 years. Severe hypoglycaemia simply has to be avoided. The newer longer-acting insulins may help in this respect.
Older evidence from a meta-analysis shows that there is the potential to reduce progress to clinically significant diabetic nephropathy by early use of ACE inhibitors (ACE Inhibitors in Diabetic Nephropathy Trialist Group, 2001).
Easiest to implement in most of our patients with type 1 diabetes is lipid-lowering. In a Swedish study of 24230 patients with type 1 diabetes (also alongside), lipid-lowering (97% statins) was associated with a reduction in CVD by 40%, stroke by 44% and acute myocardial infarction by 22%. There was also a reduction in all-cause mortality of 44%. The follow-up period was only 6 years of treatment. It is very important to state that only 5387 out of the 24230 were on lipid-lowering therapy. The potential for reducing CVD complications and death is, therefore, substantial, as only 22.2% appear to be on this basic lipid-lowering treatment. The number needed to treat to save one death per year was 297 treatment-years. This seems high, but equates to only around £4500 to save a life, as statins only cost approximately £15 a year.
NICE guidelines for type 1 diabetes have given us the remit to implement a widespread lipid-lowering strategy (NICE, 2015). All patients over the age of 40 years should be considered for statin treatment (atorvastatin 20 mg od) or, if they have had type 1 diabetes for 10 years or more, at any age. Clearly, effective contraception is essential in women of child-bearing potential.
I would like to end by keeping the key clinical messages simple. There is a compelling evidence base to suggest that the life-years lost to type 1 diabetes can be reduced. We need to renew our focus on the triple shield of good glycaemic control (good early control and avoiding severe hypoglycaemia), blood-pressure-lowering and lipid-lowering treatment with a statin.
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9 Nov 2023