Diabetes type 2 patients are at an increased risk for developing an infection and vascular disease, including coronary artery disease. Lycopene attenuated T cell-dependant adaptive immune response, probably by increasing total antioxidant capacity of the serum. When type 2 diabetes mellitus patients were treated with physiological doses of lycopene the ratio of total antioxidant capacity to malondialdehyde (end-product of lipid peroxidation ) increased significantly. Increased lycopene levels also resulted in levels of IgM. Lycopene could prevent the uptake of oxidized LDL by macrophages and inhibit the formation of foam cell, thereby reducing the risk for cardiovascular disease . Similar results were obtained by Neyestani and co-workers. The scientists from Shaheed Beheshti University of Medical Sciences in Tehran found lycopene might attenuate pro-arherogenic humoral immune response in patients with type 2 diabetes mellitus. Diabetic patients were treated daily with 10 lycopene for 8 weeks. The found that lycopene significantly increased the ratio of total antioxidant capacity to malondialdehyde, reduced the level of serum IgG and increased that of IgM .
Diabetic neuropathies, such as neuropathic pain, are neuropathic disorders caused by diabetes mellitus. They are the result of injury involving small blood vessels that supply nerves. Neuropathic pain is very difficult to treat and require the use of antinociceptives. The classical antinociceptives can cause toxic side effects and are not always offer adequate pain relieve. A study by Kuhad et al. investigated the effect of treatment of diabetic mice with lycopene. The mice were first injected with streptozotin, a drug an animal model for Type 1diabetes, and then orally administered with lycopene. The diabetic mice showed increased sensitivity to pain, lower weight and increased plasma glucose level. Treatment with lycopene significant reduced sensitivity to pain, probably by inhibiting the release of nitric oxide and tumour necrosis factor-alpha . A study conducted by the Department of Medicine, Brigham and Women's Hospital, Boston, concluded that there was no significant association between the intake of lycopene or lycopene-containing food and diabetes mellitus type 2. This prospective cohort study involved more than 35,000 women who were following during a period of 10 years. The woman were divided in 4 groups depending on the weekly intake of tomato based food products and found that the relative risk of diabetes mellitus type 2 was similar in all groups .
 Neyestani TR, Shariatzadeh N, Gharavi A, Kalayi A, Khalaji N. "Physiological dose of lycopene suppressed oxidative stress and enhanced serum levels of immunoglobulin M in patients with Type 2 diabetes mellitus: a possible role in the prevention of long-term complications." J Endocrinol Invest. 2007 Nov;30(10):833-8.
 Kuhad A, Sharma S, Chopra K. "Lycopene attenuates thermal hyperalgesia in a diabetic mouse model of neuropathic pain." Eur J Pain. 2007 Dec 3.
 Neyestani TR, Shariat-Zadeh N, Gharavi A, Kalayi A, Khalaji N. "The opposite associations of lycopene and body fat mass with humoral immunity in type 2 diabetes mellitus: a possible role in atherogenesis. " Iran J Allergy Asthma Immunol. 2007 Jun;6(2):79-87.
 Wang L, Liu S, Manson JE, Gaziano JM, Buring JE, Sesso HD. "The consumption of lycopene and tomato-based food products is not associated with the risk of type 2 diabetes in women." J Nutr. 2006 Mar;136(3):620-5.