Variable scope question

I'm have some issues understanding what is going on in the below code.  When I run the first code block i get a valid return value in rdac from an I2C device.  The returned value checks out with the parts data sheet.  Here is the code that works.

//*****************************************************************************
//
// interrupts.c - Interrupt preemption and tail-chaining example.
//
// Copyright (c) 2012-2013 Texas Instruments Incorporated.  All rights reserved.
// Software License Agreement
// 
// Texas Instruments (TI) is supplying this software for use solely and
// exclusively on TI's microcontroller products. The software is owned by
// TI and/or its suppliers, and is protected under applicable copyright
// laws. You may not combine this software with "viral" open-source
// software in order to form a larger program.
// 
// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
// DAMAGES, FOR ANY REASON WHATSOEVER.
// 
// This is part of revision 1.1 of the EK-TM4C123GXL Firmware Package.
//
//*****************************************************************************

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_nvic.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"
#include "driverlib/i2c.h"


uint32_t rdac;

//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
}
#endif


//*****************************************************************************
//
// I2C ISR
//
//*****************************************************************************
void I2C_ISR()
{



	I2CMasterIntClear(I2C1_BASE);
}






//*****************************************************************************
//
// Get RDAC Value
//
//*****************************************************************************
int GetRDAC()
{
	uint32_t value;

    //
    // Send I2C read instruction
    //
    I2CMasterDataPut(I2C1_BASE, 0x08);	// MSB read command
    I2CMasterControl(I2C1_BASE, I2C_MASTER_CMD_BURST_SEND_START);
    while(I2CMasterBusy(I2C1_BASE));

    I2CMasterDataPut(I2C1_BASE, 0x00);	// LSB read command
    I2CMasterControl(I2C1_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH);
    while(I2CMasterBusy(I2C1_BASE));

    //
    // Read RDAC reg
    //
    I2CMasterSlaveAddrSet(I2C1_BASE, 0x2F, true);


    I2CMasterControl(I2C1_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START);
    while(I2CMasterBusy(I2C1_BASE));

    value = (I2CMasterDataGet(I2C1_BASE)) << 8;

    I2CMasterControl(I2C1_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);
    while(I2CMasterBusy(I2C1_BASE));

    value += I2CMasterDataGet(I2C1_BASE);


    SysCtlDelay(100);


	return value;
}



int main(void)
{

	rdac = 0;


    //
    // Enable lazy stacking for interrupt handlers.  This allows floating-point
    // instructions to be used within interrupt handlers, but at the expense of
    // extra stack usage.
    //
    FPULazyStackingEnable();

    //
    // Set the clocking to run directly from the crystal.
    //
    SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
    //SysCtlClockSet(SYSCTL_SYSDIV_2_5 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ | SYSCTL_OSC_MAIN);



    //
    // Enable GPIOA and set pins to I2C1
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C1);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
    GPIOPinTypeI2C(GPIO_PORTA_BASE, GPIO_PIN_7);
    GPIOPinTypeI2CSCL(GPIO_PORTA_BASE, GPIO_PIN_6);
    GPIOPinConfigure(GPIO_PA6_I2C1SCL);
    GPIOPinConfigure(GPIO_PA7_I2C1SDA);


    //
    // Setup I2C1
    //

    I2CMasterInitExpClk(I2C1_BASE, SysCtlClockGet(), false);
    I2CMasterSlaveAddrSet(I2C1_BASE, 0x2F, false);




    //
    // Enable interrupts to the processor.
    //
    ROM_IntMasterEnable();









    //
    // Loop forever.
    //
    while(1)
    {


    	rdac = GetRDAC();

    	SysCtlDelay(1);


        for(;;){}


    }
}

When I comment out the

SysCtlDelay(1);

instruction and immediately hit the for loop after the GetRDAC() function CCS shows 0 for rdac in the watch window.  When I have the delay in i get the valid value as expected.  The rdac variable is a global variable.  Why can't the value be seen in watch without the delay?  This may be a dumb question, but I would like some guidance regarding this if possible so if I am making a dumb mistake I can correct it. 

Also, this is a working I2C conafiguration for the Tiva C launchpad (TM4C123GH6PMI) so feel free to use it.  It configures I2C1.

Thanks,

Rob