As commodity indexes surged to record highs Tuesday, an economist and analyst offered time-tested advice on the macroeconomic and portfolio implications of the market's latest investment obsession of the moment.

Economist Glen Langan told BloggingStocks Tuesday that the steep climbs in soybean, wheat, platinum, coal and gasoline all speak to, for the most part, a secular trend that the world's major economic regions will have to address at some point: rising commodity prices that outstrip the developed and developing worlds' ability to absorb those price increases.

Langan said demand for commodities and raw materials remains above average, even as prices have risen, due to strong emerging market economic growth. Typically, after extended bull runs, either demand recedes or prices drop. Prices, so far, haven't dropped. The UBS Bloomberg Constant Maturity Commodity Index gained as much as 2.8% to 1,441.593, the highest ever, Bloomberg News reported Tuesday. "So unless we've suspended a law of economics, growth in these regions has to slow, at least somewhat," Langan said.