ADA: Neuropathy Most Likely to Strike in Type 2 Diabetes

CHICAGO, June 27 -- Painful neuropathy is more common in patients with type 2 diabetes than in those with type 1, possibly, researchers suggest, because of a link with the metabolic syndrome.

In an observational study, painful diabetic polyneuropathy was three times more common among type 2 patients than type 1 patients (17.9% versus 5.8%), reported Ides M. Colin, M.D., Ph.D., of CHR-S. Joseph Medical Center in Mons, Belgium, and colleagues.

This type of neuropathy was independently associated with three components of the metabolic syndrome-obesity, low HDL cholesterol, and high triglyceride levels--they said at the American Diabetes Association meeting here.

"The higher prevalence of diabetic polyneuropathy in type 2 diabetic patients could be due to the involvement of metabolic syndrome-associated disturbances," they wrote.

Because the epidemiology of painful diabetic polyneuropathy had not been well characterized, the researchers conducted a cross-sectional study that included 1,111 patients at 40 Belgian diabetes clinics; 344 had type 1diabetes and 767 had type 2.

The researchers tested for neuropathy in patients' feet using a monofilament for sensory perception and a device called the Neuropen for pain sensation. Participants also completed a questionnaire on characteristics of the pain sensation.

Nearly half of the patients overall complained of pain on the visual analog scale. Patients with type 2 diabetes reported it more frequently than did those with type 1 (53.6% versus 34.9%).

The occurrence of diabetic polyneuropathy was significantly higher among type 2 diabetes patients than type 1 patients (50.8% versus 25.6%, P=0.0007).

The prevalence of painful diabetic polyneuropathy showed the same significant difference (17.9% versus 5.6%).

Factors associated with higher diabetic neuropathy in a multivariate analysis were male gender (P=0.02), increasing age (P<0.0001), type 2 diabetes (P=0.02), increasing duration of the disease (P=0.0006), and HDL cholesterol at or below 40 mg/dL for men or 50 mg/dL for women (P<0.0001).

The strongest predictors of neuropathy in a bivariate analysis were foot problems (odds ratio 10.5, P<0.0001) and low HDL cholesterol (OR 2.14, P<0.0001).

Independent predictors of painful diabetic neuropathy were:

• Low HDL cholesterol (OR 2.17, 95% confidence interval 1.38 to 3.41, P=0.0008).
• Triglyceride levels at or above 150 mg/dL (OR 1.76, 95% CI 1.13 to 2.75, P=0.01).
• Obesity (OR 1.62, 95% CI 1.05 to 2.49, P=0.03).
• Nephropathy (OR 1.69, 95% CI 1.10 to 2.59, P=0.02).
• Age (OR 1.47 per decade, 95% CI 1.20 to 1.81, P=0.0003).
• Diabetes duration (OR 1.14 per five years, 95% 1.02 to 1.28, P=0.02).

The researchers concluded that neuropathy and painful neuropathy are mainly associated with type 2 diabetes, potentially via the metabolic syndrome, which encompassed the majority of the strong predictors found.

"Diabetic neuropathy and painful neuropathy are often associated with other complications, as well as modifiable risk factors including some of those related to the metabolic syndrome," they wrote.