Writing a script to plot cubic spline approximations

Write a script called inteffect that will plot cubic spline approximations to each set of data. Use the given file quad3 to integrate the data. Your script should produce a figure (use subplot).

Data:
time = [0,10,20,30,40,50,60]
glucose = [102, 114, 122, 132, 115, 107, 100]
insulin = [11,26,36,47,39,27,15]

quad3.m:
function I = quad3(x, f)
%
% I = quad3(x, f);
%
% This function integrates tabular data using cubic splines.
%
% Input: x, f - vectors containing the tabular data
% Output: I - approximation of the integral
%
S = spline(x, f);
N = length(x);
I = 0;
for i = 1:N-1
h = x(i+1) - x(i);
I = I + (h/6)*(f(i) + 4 * ppval(S, (x(i) + x(i+1))/2) + f(i+1));
end

Modify quad3 and write a new function m-file quadp which uses pchip instead of spline. This is an easy modification.

I am not sure how to plot a graph of the data which connects the points using the spline.