Three types of "mid-band" lipoproteins in non-insulin-dependent diabetes mellitus: relation to metabolic abnormalities and vascular complications.

A number of fine bands which occur in positions between the beta- and pre-beta-lipoproteins in polyacrylamide gell electrophresis are called mid-bands (MB). In this study, the relationship between the occurrence of these MB and metabolic abnormalities or vascular complications was evaluated in 181 patients with non-insulin-dependent diabetes mellitus (NIDDM). The incidence of MB in diabetic patients was significantly higher than that in 149 healthy control subjects (35 vs. 20%, p < 0.01). Analysis according to the type of MB revealed that the incidence of the central type in diabetic patients was significantly higher than that in healthy control subject (11 vs. 5%, p < 0.05). When the values of HbAlc were elevated, the incidence of MB and its central type slightly increased. The occurrence of the lower type of MB showed no relationship with the levels of HbAlc. The incidence of MB and its central type were significantly higher in patients with type IIb hyperlipidemia (86 and 41%, respectively) and with type IV hyperlipidemia (63 and 25%) than in those with normolipidemia (21 and 5%) (p < 0.01 of all). The incidence of the lower type of MB was significantly higher in patients with type IIa hyperlipidemia (25%) and with type IIb hyperlipidemia (36%) than in those with normolipidemia (11%) (p < 0.05, p < 0.01, respectively). There was no significant difference in the occurrences of MB and of the central and lower types of MB between the normolipidemic patients and healthy control subjects. The incidence of MB and its central type were significantly higher in patients with nephropathy (54 and 23%, respectively) than in those without nephropathy (32 and 9%) (p < 0.05 of all). There was no significant difference in the incidence of lower type of MB between patients with and without nephropathy. These results indicate that the incidence of central type of MB may be high in NIDDM, and that the occurrence of central type may be associated with abnormal metabolism of glucose or lipid and with diabetic nephropathy.