The present study deals with the detection of elements responsible for glycemic potential of ripe and unripe fruit peel aqueous extracts of Psidium guajava (P. guajava). Treatment with the aqueous extract of unripe fruit peel showed a significant fall of 17.5% (p<0.001) in blood glucose levels (BGLs) of normal rats during fasting blood glucose (FBG) test with a dose of 400 mg/kg bw. In sub‐diabetic rats, a fall of 19.8% (p<0.001) was observed with the same dose during a glucose tolerance test (GTT). The significant fall observed in FBG, post prandial glucose (PPG) and urine sugar levels of severely diabetic rats was 20.7%, 17.5% (p<0.05), and 66.6% (p<0.01), respectively. On the contrary, the effect of ripe fruit peel aqueous extract showed a regular rise of 24.4% (p<0.01) in BGL of normal rats and of 90.0% (p<0.001) in sub‐diabetic rats. Laser Induced Breakdown Spectroscopy (LIBS) has been used for the identification of elements responsible for the glycemic potential of fruit peel aqueous extracts of P. guajava. Concentration of Mg was found higher in unripe fruit peel aqueous extract than in the ripe fruit peel aqueous extract whereas the concentration of K was found lower in the extract of unripe fruit peel than in the extract of ripe fruit peel. Thus, the LIBS results help in defining the role of Mg and K in diabetes management. However, the concentrations of other minerals, like Na, N, O, and C, are nearly the same in both of the extracts.