Analysis of 8,653 participants followed from birth to age 49, plus 13,795 UK Biobank participants aged 40-79, reveals that metabolic health stratification emerges as early as ages 3-12 and remains stable throughout life. Two high-risk metabolic subgroups showed increased waist-to-height ratios from childhood, persistently elevated C-reactive protein, and rapidly rising fasting insulin between ages 30-49. These patterns translated into dramatic disease risks: over 13-fold higher diabetes risk and 2.5-fold higher ischemic heart disease risk compared to the healthiest subgroup. This represents one of the longest longitudinal metabolic studies ever conducted, providing unprecedented evidence that cardiometabolic destiny may be largely determined in early childhood. The findings challenge conventional thinking about when metabolic dysfunction begins and suggest critical intervention windows may occur much earlier than previously recognized. However, as an unreviewed preprint, these results require peer validation before clinical application. The study's observational design also cannot establish causation, and the predominantly European population may limit generalizability to other ethnicities.