Objective: The implications of celiac disease (CD) in adult patients with type 1 diabetes are unknown, with respect to diabetes-related outcomes including glycemic control, lipids, microvascular complications, quality of life, and the effect of a gluten-free diet (GFD). We identified CD in adults with type 1 diabetes and investigated the effect of a GFD on diabetes-related complications.
Research design and methods: This was a case-control study conducted at a U.K. teaching hospital. Patients with type 1 diabetes aged >16 years (n = 1,000) were assessed for CD. HbA1c, lipid profile, quality of life, retinopathy stage, nephropathy stage, and degree of neuropathy before and after 1 year on a GFD were assessed.
Results: The prevalence of CD was 33 per 1,000 subjects (3.3% [95% CI 2.3–4.6]). At diagnosis of CD, adult type 1 diabetic patients had worse glycemic control (8.2 vs. 7.5%, P = 0.05), lower total cholesterol (4.1 vs. 4.9, P = 0.014), lower HDL cholesterol (1.1 vs. 1.6, P = 0.017), and a higher prevalence of retinopathy (58.3 vs. 25%, P = 0.02), nephropathy (41.6 vs. 4.2%, P = 0.009), and peripheral neuropathy (41.6 vs. 16.6%, P = 0.11). There was no difference in quality of life (P > 0.1). After 1 year on a GFD, only the lipid profile improved overall, but in adherent individuals HbA1c and markers for nephropathy improved.
Conclusions: Adults with undetected CD and type 1 diabetes have worse glycemic control and a higher prevalence of retinopathy and nephropathy. Treatment with a GFD for 1 year is safe in adults with type 1 diabetes and does not have a negative impact on the quality of life.
Long-term microvascular and neurologic complications are responsible for major morbidity and mortality in type 1 diabetes (1). Intensive glycemic control reduces these complications and improves quality of life (1). Even patients with good glycemic control have complications, suggesting that other factors increase the risk (2). Coexisting medical problems may be a confounding factor when managing glycemic control (2). The association between celiac disease (CD) and type 1 diabetes was recognized over 30 years ago, particularly by pediatricians. The prevalence of CD in patients with adult type 1 diabetes has been reported as 1.8–8.4% (3–6). Despite a large number of prevalence studies, other important clinical factors have not been well investigated, including glycemic control, quality of life, microvascular complications, cardiac risk factors, and bone mineral density.
Investigations of the effect of CD on glycemic control have been conflicting, with some studies showing improvement (7) and some deterioration (4,8) and others showing no effect (9). The difficulty in interpreting these studies is that most involve pediatric populations and are small, retrospective, and uncontrolled, leaving this question unanswered. There have been no quality-of-life assessments before and after the diagnosis of CD to assess the impact of the diagnosis and a subsequent gluten-free diet (GFD) (3). Adapting to a GFD with the restrictions of a diabetic diet may negatively impact quality of life.
Peripheral neuropathy affects up to 30% of patients with adult type 1 diabetes and is a major cause of morbidity (1). Neuropathy is associated with both type 1 diabetes and CD; therefore, patients with both conditions may have a higher prevalence (10,11). In gluten-sensitive neuropathy, the pathophysiological changes lie in the humoral immune response, and a GFD seems to be beneficial (12,13). There are no studies examining neuropathy in patients with type 1 diabetes and CD or the effect of a GFD. One study examined whether CD may contribute to autonomic neuropathy in a cohort of patients with type 1 diabetes. They found no difference in the prevalence of positive antibodies in patients with and without autonomic neuropathy (14).
Two previous studies have examined the effect of CD on diabetic nephropathy but were conflicting (15,16). There are currently no studies examining the prevalence of retinopathy in individuals with both type 1 diabetes and CD.
Recent data in nondiabetic CD cohorts have shown a reduced risk of ischemic heart disease, possibly attributed to lower cholesterol levels and a lower prevalence of hypertension (17). Reduced bone mineral density has been associated with both CD and type 1 diabetes, but there are little data on people with both conditions (18). The aim of our study was to identify undetected CD in adult patients with type 1 diabetes and investigate the effect on diabetes-related complications before and after a GFD
