The use of depot medroxyprogesterone acetate appears to be associated with slightly higher levels of fasting glucose and insulin ...
... Compared to nonhormonal users, the investigators found that depot medroxyprogesterone acetate users, but not oral contraceptive pill users, experienced slightly greater increases in glucose and insulin ... insulin levels showed an upward trend for the first 18 months of depot medroxyprogesterone acetate use and then remained relatively stable ... those who were overweight or obese showed slightly higher increases in insulin and glucose levels."
Despite this finding and the obvious implications for increased risk of developing gestational diabetes and type two diabetes, the authors conclude that, "data from this longitudinal study are reassuring overall regarding the effects of these two contraceptives on insulin-glucose metabolism,"
Non-hormonal, natural methods of contraception have no side effects and are very effective if used correctly.