Whether pancreatic steatosis has a local or systemic effect, like ectopic fat of other major organs, remains unknown. Data on the influence of pancreatic steatosis on microvascular complication are rare. Therefore, we investigated the relationship between pancreatic steatosis and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM).

The attenuation of three pancreatic regions (head, body, and tail) and the spleen (S) in 186 patients with T2DM was measured using non-enhanced computed tomography imaging. We used three parameters for the assessment of pancreatic steatosis (‘P’ mean: mean attenuation of three pancreatic regions; P–S: difference between ‘P’ mean and ‘S’; P/S: the ‘P’ mean to ‘S’ ratio). The presence of DR was assessed by an expert ophthalmologist using dilated fundoscopy.

The average P mean was 29.02 Hounsfield units (HU), P–S was −18.20 HU, and P/S was 0.61. The three pancreatic steatosis parameters were significantly associated with the prevalence of DR in non-obese T2DM patients. In the non-obese group, the odds ratios of P mean, P–S, and P/S for the prevalence of DR, after adjustment for age, sex, and glycosylated hemoglobin level, were 2.449 (P=0.07), 2.639 (P=0.04), and 2.043 (P=0.02), respectively.

In this study, pancreatic steatosis was significantly associated with DR in non-obese patients with T2DM. Further studies are necessary to clarify the causal relationship between pancreatic steatosis and the development of DR.

Insulin-mediated glucose uptake in insulin target tissues is correlated with interstitial insulin concentration, rather than plasma insulin concentration. Therefore, insulin delivery to the interstitium of target tissues is very important, and the endothelium may also play an important role in the development of insulin resistance.

After treating bovine aortic endothelial cells with angiotensin II (ATII), we observed the changes in insulin binding capacity and the amounts of insulin receptor (IR) on the cell membranes and in the cytosol.

After treatment of 10^-7M ATII, insulin binding was decreased progressively, up to 60% at 60 minutes (P<0.05). ATII receptor blocker (eprosartan) dose dependently improved the insulin binding capacity which was reduced by ATII (P<0.05). At 200 µM, eprosartan fully restored insulin binding capacity, althogh it resulted in only a 20% to 30% restoration at the therapeutic concentration. ATII did not affect the total amount of IR, but it did reduce the amount of IR on the plasma membrane and increased that in the cytosol.

ATII decreased the insulin binding capacity of the tested cells. ATII did not affect the total amount of IR but did decrease the amount of IR on the plasma membrane. Our data indicate that ATII decreases insulin binding by translocating IR from the plasma membrane to the cytosol. The binding of insulin to IR is important for insulin-induced vasodilation and transendothelial insulin transport. Therefore, ATII may cause insulin resistance through this endothelium-based mechanism.