Nicotinamide overload may play a role in the development of type 2 diabetes

Figure 6 Role of skin in nicotinamide metabolism and insulin resistance. A: Representative HPLC chromatograms showing changes of sweat nicotinamide (NM) and N¹-methylnicotinamide (NMN) concentrations in a subject before and 1, 2 and 3 h after 100 mg nicotinamide loading. 1 and 2 in Aa are NM and internal standard N¹-ethylnicotinamide, respectively; 1 and 2 in Ab are NMN and internal standard N¹-ethylnicotinamide, respectively; B: Summary of the measurements shown in A. ^bP < 0.0001 vs control; C: Comparison of plasma NMN and insulin levels, muscle and liver glycogen contents, and blood glucose between sham-burn (n = 7) and burn (n = 11) rats after glucose load. FBG: Fasting blood glucose; GTT: Blood glucose 1 h after glucose injection. Bar graphs show mean ± SD. ^cP < 0.05, ^dP < 0.01 vs control.