medwireNews: Patients with rheumatoid arthritis (RA) or osteoarthritis and comorbid adult-onset type 2 diabetes have a clinical profile of severe diabetes with poor glycemic control, researchers report.
These findings are based on an observational study of 167 individuals with type 2 diabetes and either RA (n=118) or osteoarthritis (n=49). The average age was 64 years for people with RA and 70 years for those with osteoarthritis, and approximately three-quarters of individuals in both groups were women.
The investigators report in Rheumatology that people in both groups had “suboptimal metabolic control” and a “high frequency of cardiovascular risk factors.”
Specifically, average glycated hemoglobin (HbA1c) levels were 7.0% (53 mmol/mol) among people with RA and 7.3% (56 mmol/mol) in those with osteoarthritis; a respective 27.9% and 26.5% required insulin, and the prevalence of complications (neuropathy, retinopathy, and nephropathy) ranged from 8.9% to 19.2%. The mean BMI was 27.7 and 31.8 kg/m2 in the RA and osteoarthritis groups, respectively, and a corresponding 70% and 76% had hypertension.
Despite both groups having “similar [type 2 diabetes] characteristics,” the study authors note that insulin resistance correlated with age and obesity among patients with osteoarthritis, but “related to the joint and systemic inflammatory activity of the disease” in those with RA.
People with RA also had a significantly greater degree of insulin resistance than those with osteoarthritis after adjustment for age, BMI, and corticosteroid use, with a HOMA2-IR measure of 1.94 versus 1.10.
In a multivariate analysis, having moderate or high RA disease activity – indicated by a DAS28 score above 3.2 points – was significantly associated with decreased insulin sensitivity as indicated by a HOMA2-S measure of less than 42 (odds ratio [OR]=4.46), as was having C-reactive protein levels above 10 mg/L (OR=6.92).
“These findings may have therapeutic implications, with the potential targeting of insulin resistance through the treatment of joint and systemic inflammation,” say Jérôme Avouac (Université de Paris, France) and co-authors.
The team also evaluated the impact of RA treatment on metabolic indices, finding that the use of tumor necrosis factor inhibitors was significantly associated with insulin sensitivity, but not with glycemic control, suggesting that “further prospective studies are necessary to determine whether this therapeutic class may improve the outcome of [type 2 diabetes].”
Other RA treatments – including alternative biologics (tocilizumab, abatacept, and rituximab), methotrexate, hydroxychloroquine, and low-dose corticosteroids – were not significantly associated with insulin sensitivity or glycemic control.
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